Anxiolytic compounds

ABSTRACT

The present invention relates to chemical compounds of general formula (I) 
                         
which may possess useful therapeutic activity in a range of central nervous system disorders, and in particular, anxiety disorders.

RELATED APPLICATION

The present application is a continuation of and claims priority under35 U.S.C. §120 to U.S. patent application, U.S. Ser. No. 12/311,872,filed Nov. 23, 2009, now U.S. Pat. No. 8,293,737, which is a nationalstage filing under 35 U.S.C. §371 of international PCT application,PCT/AU2007/001566, filed Oct. 16, 2007, which claims priority under 35U.S.C. §119(e) to U.S. provisional patent application, U.S. Ser. No.60/851,983, filed Oct. 16, 2006, each of which is incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to chemical compounds andmethods for their use and preparation. In particular, the inventionrelates to chemical compounds which may possess useful therapeuticactivity in a range of central nervous system disorders, and inparticular, anxiety disorders. The invention also relates to the use ofthese compounds in methods of therapy and the manufacture of medicamentsas well as compositions containing these compounds.

BACKGROUND OF THE INVENTION

γ-Aminobutyric acid (GABA) is one of the major inhibitory amino acidtransmitters in the mammalian central nervous system (CNS) and acts bybinding to specific receptors in the plasmamembrane of both pre- andpostsynoptic neurons. The binding of GABA to specific receptors causesthe opening of ion channels in the cell membrane which allows either theflow of negatively-charged chloride ions into the cell orpositively-charged potassium ions out of the cell. This typicallyresults in a negative change in the transmembrane potential whichusually causes hyperpolarisation.

There were once thought to be three types of receptors for GABA in themammalian CNS, designated A, B, and C. GABA_(A) and GABA_(C), receptorsare GABA-gated chloride ion-conducting channels while the GABA Breceptor is a member of the G-protein receptor superfamily. GABA_(A) andGABA_(C), receptors were initially distinguished from one another bytheir sensitivity to the ligand bicuculline with the former beingantagonised by it while the latter were insensitive. However, it hasbecome increasingly clear since the mid-1990s that the GABA_(A) andGABA_(C), receptors are simply variants of the same GABA-gated chloridechannel. Therefore, these receptors are now denoted by the “GABA_(A)”receptor designation. While varieties of the GABA_(A) receptor are foundall over the CNS, the GABA_(C), receptors (GABA_(A) variant also nowdefined variously as GABA_(AOr)) are primarily found in the retina.

The GABA_(A) receptor is a member of the Cys-loop ligand-gated ionchannel superfamily which also includes the glycine, 5-hydroxytryptamine(5-HT, serotonin), and nicotinic acetylcholine receptors. Receptors ofthis superfamily consist of pentamers of homologous subunits arrangedaround a central ion-conducting channel. There are 19 different subunitgenes—not including alternatively-spliced variants such as the short (S)and long (L) forms of the 1-6, γ1-3,αγ2 subunit—divided into eightsubunit classes: β1-3, η, ρ1-2, δ, π, ε (listed according to sequencerelatedness). It is presumed that these subunits all arose as a resultof gene duplications of an original sequence. Within a class of subunitsthere is approximately 70% sequence identity, and between subunitclasses approximately 30% sequence identity. The majority of GABA_(A)receptor subtypes in the mammalian brain contain at least one α, β, andγ subunit. Most GABA_(A) receptors consist of assemblies of these threesubunit classes. The most abundantly expressed isoform of the GABA_(A)receptor in the mammalian brain is composed of α1, β2, and γ2, and thelikely stoichiometry is two α, two β and one γ subunit arranged aroundthe ion channel anti-clockwise γ-β-α-β-α as seen from the synapticcleft. GABA_(A) receptors of these subtypes are overwhelminglynumerically dominant in the CNS.

Each subunit of the GABA_(A) receptor has a common structure consistingof a large amino-terminal portion, four transmembrane helices—designatedtransmembrane (TM) one to four, and a short, cytoplasmic loop toward thecarboxy-terminus that is composed of the loop extending between TM3 andTM4. The receptor subunits are arranged pseudo-symmetrically so that theTM2 helix of each subunit lines the central pore. Recent models of thestructure of the GABA_(A) receptor have been based on the crystalstructure of the related acetylcholine binding protein.

GABA_(A) receptors can exist in at least three different conformations:open, closed, and desensitised. Activation of the GABA_(A) receptor byGABA binding to the GABA site allows chloride ions to flow through thecentral pore and hyperpolarise the neuron, decreasing the probabilitythat it will propagate an action potential. In this activity, theGABA_(A) receptor does not differ from any other ligand-gated ionchannel. However, up to 14 different ligand binding sites have beenproposed to account for the modulation of GABA. Thus amongneurotransmitter receptors, GABA_(A) receptors are unique in view of thefact that their are a large number of ligands that can bind andallosterically modulate their function.

Binding of ligands to the GABA_(A) receptor can alter the conformationof the GABA_(A) receptor in such a way as to enhance or diminish thechloride flux in response to GABA binding. Some anesthetics (e.g.etomidate and pentobarbitone) both enhance chloride flow in response toGABA binding as well as activating it directly in the absence of GABA.Other ligands, such as cage convulsants of the picrotoxin type, bindwithin the central pore of the receptor thus, occluding the channel andpreventing chloride flow, an effect which occurs no matter what otherligand subsequently binds. Hence, the neurophysiological effects of GABAresult from a conformational change that occurs upon binding of GABA tothe GABA_(A) receptor.

The most widely studied and characterised class of allosteric modulatorsof the GABA-GABA_(A) receptor complex are a class of compounds known asbenzodiazepines (an example of which is diazepam a 1,4-benzodiazepine,commonly known as Valium®) which interact with the benzodiazepine(BZ)-site on the GABA_(A) receptor. Possession of a γsubunit and aparticular type of α subunit (1, 2, 3, or 5) is required to confersensitivity to this class of compounds.

Classical benzodiazepines do not directly open the ion channel, ratherthey allosterically modify the GABA_(A) receptor upon binding,potentiating the effect of GABA binding when there is a submaximalconcentration of GABA present and thereby increasing hyperpolarizingresponses and neuronal inhibition. Benzodiazepines produce systemiceffects that include sedation, amnesia, muscle relaxation, andanxiolysis. Hence, these compounds are widely used as anxiolytics,sedative-hypnotics, muscle relaxants, and anti-convulsants.Benzodiazepines were the most widely prescribed class of drugs duringthe 1970s and, as a group, have one of the largest therapeutic indexes.Although the GABA_(A) binding site is called the benzodiazepine site,drugs of other types can also bind and allosterically modify thereceptor at that site. These include drugs with β-carboline,imidazopyridine, and triazolopyridazine structures. It is believed thatcompounds acting as BZ agonists at α₁βγ₂, α₂βγ₂ or α₃βγ₂ subtypes willpossess desirable anxiolytic activity. Such modulators of the BZ bindingsite of GABA_(A) are known herein as “GABA_(A) receptor agonists”.

However, while the 1,4-benzodiazepines are an effective class ofanxiolytics they possess the often unwanted side-effect of sedation. Itis postulated that at least some of the unwanted sedation experienced byknown anxiolytic drugs which act through the BZ binding site is mediatedthrough GABA_(A) receptors containing the α₁-subunit. This has beendetermined primarily from the effects displayed by the well studiedhypnotic agents Alpidem and Zolpidem which are α₁-selective GABA_(A)receptor agonists.

Thus in order to minimise the sedation effect, while still maintainingeffective anxiolytic activity recent research has turned to findingGABA_(A) receptor agonists which interact more favourably with the α₂and/or α₃ subunit than with α₁.

SUMMARY OF THE INVENTION

A targeted medicinal chemistry program was initiated, with the aim ofproducing compounds with improved solubility, metabolic stability, andefficacy.

Briefly, the physicochemical profile and stability in microsomepreparations was determined for each compound by standard methods. Thestrategy used to identify compounds of interest was as follows.Compounds that exhibited improved solubility and stability were thentested for efficacy in the light/dark box, a mouse model of anxiety thatwas used as the primary efficacy screen. Compounds which performed wellin the initial Light/Dark test were then assessed for effects onspontaneous motor activity in mice in a modified Open Field (dark)apparatus. Compounds which exhibited sedative side effects were nottested further. In vivo assessment of the anxiolytic and sedativeproperties of the compounds allowed for the identification of GABA_(A)receptor agonists and also for anxiolytic compounds that interacted withother targets, both known and novel.

The present invention provides compounds of formula (I) and saltsthereof;

-   where A, E, and D are independently selected from CR′ (where R′ is    selected from H, carboxyl, cyano, dihalomethoxy, halogen, hydroxy,    nitro, pentahaloethyl, phosphono, phosphorylamino, phosphinyl,    sulfo, trihaloethenyl, trihalomethanethio, trihalomethyl,    trihalomethoxy, optionally substituted acyl, optionally substituted    acylamino, optionally substituted acylimino, optionally substituted    acyliminoxy, optionally substituted acyloxy, optionally substituted    arylalkyl, optionally substituted arylalkoxy, optionally substituted    alkenyl, optionally substituted alkenyloxy, optionally substituted    alkoxy, optionally substituted alkyl, optionally substituted    alkynyl, optionally substituted alkynyloxy, optionally substituted    amino, optionally substituted aminoacyl, optionally substituted    aminoacyloxy, optionally substituted aminosulfonyl, optionally    substituted aminothioacyl, optionally substituted aryl, optionally    substituted arylamino, optionally substituted aryloxy, optionally    substituted cycloalkenyl, optionally substituted cycloalkyl,    optionally substituted heteroaryl, optionally substituted    heterocyclyl, optionally substituted oxyacyl, optionally substituted    oxyacylamino, optionally substituted oxyacyloxy, optionally    substituted oxyacylimino, optionally substituted oxysulfinylamino,    optionally substituted oxysulfonylamino, optionally substituted    oxythioacyl, optionally substituted oxythioacyloxy, optionally    substituted sulfinyl, optionally substituted sulfinylamino,    optionally substituted sulfonyl, optionally substituted    sulphonylamino, optionally substituted thio, optionally substituted    thioacyl, and optionally substituted thioacylamino) or N, and    wherein at least one of A, E and D is N;    -   X represents O or NR″ (where R″ is selected from H, optionally        substituted alkyl, optionally substituted aryl, optionally        substituted cycloalkyl, optionally substituted acyl, optionally        substituted alkenyl, optionally substituted heterocyclyl,        optionally substituted heterocyclyl, optionally substituted        heteroaryl, optionally substituted oxysulfinyl, optionally        substituted oxysulfonyl, optionally substituted sulfinyl, and        optionally substituted sulfonyl);    -   Y represents OR′″ (where R′″ is H or optionally substituted        alkyl) or NR₃R₄;    -   R represents H or optionally substituted alkyl;    -   R₁ represents optionally substituted cycloalkyl, optionally        substituted cycloalkenyl, optionally substituted alkyl,        optionally substituted acyl, optionally substituted aryl,        optionally substituted heterocyclyl, or optionally substituted        heteroaryl;    -   R₂ represents H, optionally substituted cycloalkyl, optionally        substituted alkyl, optionally substituted acyl, optionally        substituted aryl, optionally substituted alkenyl, optionally        substituted heterocyclyl, optionally substituted heteroaryl,        optionally substituted oxysulfinyl, optionally substituted        oxysulfonyl, optionally substituted sulfinyl, or optionally        substituted sulfonyl; and    -   R₃ and R₄ each independently represent optionally substituted        alkyl, or together with the N-atom optionally substituted        N-containing heteroaryl or optionally substituted N-containing        heterocyclyl.

The present invention also provides a method for treating centralnervous system disorders including the step of administering to apatient in need thereof a compound of formula (I) or a pharmaceuticallyacceptable salt thereof;

-   where A, E, and D are independently selected from CR′ (where R′ is    selected from H, carboxyl, cyano, dihalomethoxy, halogen, hydroxy,    nitro, pentahaloethyl, phosphono, phosphorylamino, phosphinyl,    sulfo, trihaloethenyl, trihalomethanethio, trihalomethyl,    trihalomethoxy, optionally substituted acyl, optionally substituted    acylamino, optionally substituted acylimino, optionally substituted    acyliminoxy, optionally substituted acyloxy, optionally substituted    arylalkyl, optionally substituted arylalkoxy, optionally substituted    alkenyl, optionally substituted alkenyloxy, optionally substituted    alkoxy, optionally substituted alkyl, optionally substituted    alkynyl, optionally substituted alkynyloxy, optionally substituted    amino, optionally substituted aminoacyl, optionally substituted    aminoacyloxy, optionally substituted aminosulfonyl, optionally    substituted aminothioacyl, optionally substituted aryl, optionally    substituted arylamino, optionally substituted aryloxy, optionally    substituted cycloalkenyl, optionally substituted cycloalkyl,    optionally substituted heteroaryl, optionally substituted    heterocyclyl, optionally substituted oxyacyl, optionally substituted    oxyacylamino, optionally substituted oxyacyloxy, optionally    substituted oxyacylimino, optionally substituted oxysulfinylamino,    optionally substituted oxysulfonylamino, optionally substituted    oxythioacyl, optionally substituted oxythioacyloxy, optionally    substituted sulfinyl, optionally substituted sulfinylamino,    optionally substituted sulfonyl, optionally substituted    sulphonylamino, optionally substituted thio, optionally substituted    thioacyl, and optionally substituted thioacylamino) or N, and    wherein at least one of A, E and D is N;    -   X represents O or NR″ (where R″ is selected from H, optionally        substituted alkyl, optionally substituted aryl, optionally        substituted cycloalkyl, optionally substituted acyl, optionally        substituted alkenyl, optionally substituted heterocyclyl,        optionally substituted heterocyclyl, optionally substituted        heteroaryl, optionally substituted oxysulfinyl, optionally        substituted oxysulfonyl, optionally substituted sulfinyl, and        optionally substituted sulfonyl);    -   R represents H or optionally substituted alkyl;    -   Y represents OR′″ (where R′″ is H or optionally substituted        alkyl) or NR₃R₄;    -   R₁ represents optionally substituted cycloalkyl, optionally        substituted cycloalkenyl, optionally substituted alkyl,        optionally substituted acyl, optionally substituted aryl,        optionally substituted heterocyclyl, or optionally substituted        heteroaryl;    -   R₂ represents H, optionally substituted cycloalkyl, optionally        substituted alkyl, optionally substituted acyl, optionally        substituted aryl, optionally substituted alkenyl, optionally        substituted heterocyclyl, optionally substituted heteroaryl,        optionally substituted oxysulfinyl, optionally substituted        oxysulfonyl, optionally substituted sulfinyl or optionally        substituted sulfonyl; and    -   R₃ and R₄ each independently represent optionally substituted        alkyl, or together with the N-atom optionally substituted        N-containing heteroaryl or optionally substituted N-containing        heterocyclyl.

The present invention also provides the use of a compound of formula (I)or a salt thereof:

-   where A, E, and D are independently selected from CR′ (where R′ is    selected from H, carboxyl, cyano, dihalomethoxy, halogen, hydroxy,    nitro, pentahaloethyl, phosphono, phosphorylamino, phosphinyl,    sulfo, trihaloethenyl, trihalomethanethio, trihalomethyl,    trihalomethoxy, optionally substituted acyl, optionally substituted    acylamino, optionally substituted acylimino, optionally substituted    acyliminoxy, optionally substituted acyloxy, optionally substituted    arylalkyl, optionally substituted arylalkoxy, optionally substituted    alkenyl, optionally substituted alkenyloxy, optionally substituted    alkoxy, optionally substituted alkyl, optionally substituted    alkynyl, optionally substituted alkynyloxy, optionally substituted    amino, optionally substituted aminoacyl, optionally substituted    aminoacyloxy, optionally substituted aminosulfonyl, optionally    substituted aminothioacyl, optionally substituted aryl, optionally    substituted arylamino, optionally substituted aryloxy, optionally    substituted cycloalkenyl, optionally substituted cycloalkyl,    optionally substituted heteroaryl, optionally substituted    heterocyclyl, optionally substituted oxyacyl, optionally substituted    oxyacylamino, optionally substituted oxyacyloxy, optionally    substituted oxyacylimino, optionally substituted oxysulfinylamino,    optionally substituted oxysulfonylamino, optionally substituted    oxythioacyl, optionally substituted oxythioacyloxy, optionally    substituted sulfinyl, optionally substituted sulfinylamino,    optionally substituted sulfonyl, optionally substituted    sulphonylamino, optionally substituted thio, optionally substituted    thioacyl, and optionally substituted thioacylamino) or N, and    wherein at least one of A, E and D is N;    -   X represents O or NR″ (where R″ is selected from H, optionally        substituted alkyl, optionally substituted aryl, optionally        substituted cycloalkyl, optionally substituted acyl, optionally        substituted alkenyl, optionally substituted heterocyclyl,        optionally substituted heterocyclyl, optionally substituted        heteroaryl, optionally substituted oxysulfinyl, optionally        substituted oxysulfonyl, and optionally substituted sulfinyl,        optionally substituted sulfonyl);    -   Y represents OR′″ (where R′″ is H or optionally substituted        alkyl) or NR₃R₄;    -   R represents H or optionally substituted alkyl;    -   R₁ represents optionally substituted cycloalkyl, optionally        substituted cycloalkenyl, optionally substituted alkyl,        optionally substituted acyl, optionally substituted aryl,        optionally substituted heterocyclyl, or optionally substituted        heteroaryl;    -   R₂ represents H, optionally substituted cycloalkyl, optionally        substituted alkyl, optionally substituted acyl, optionally        substituted aryl, optionally substituted alkenyl, optionally        substituted heterocyclyl, optionally substituted heteroaryl,        optionally substituted oxysulfinyl, optionally substituted        oxysulfonyl, optionally substituted sulfinyl, or optionally        substituted sulfonyl; and    -   R₃ and R₄ each independently represent optionally substituted        alkyl, or together with the N-atom optionally substituted        N-containing heteroaryl or optionally substituted N-containing        heterocyclyl,        in the manufacture of a medicament for the treatment of central        nervous system disorders.

DETAILED DESCRIPTION OF THE INVENTION

The invention is based on the discovery that the compounds of thegeneral formula I, as described in the above Summary of the Inventionhave useful properties as possible ligands for GABA_(A) receptors and/orother receptors and biological targets that elicit an anxiolytic effect.Such compounds have significant potential for the treatment of a varietyof disorders of the central nervous system, and in particular anxietydisorders.

“Alkyl” refers to monovalent alkyl groups which may be straight chainedor branched and preferably have from 1 to 10 carbon atoms or morepreferably 1 to 6 carbon atoms. Examples of such alkyl groups includemethyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, n-hexyl, andthe like.

“Alkylene” refers to divalent alkyl groups preferably having from 1 to10 carbon atoms and more preferably 1 to 6 carbon atoms. Examples ofsuch alkylene groups include methylene (—CH₂—), ethylene (—CH₂CH₂—), andthe propylene isomers (e.g., —CH₂CH₂CH₂— and —CH(CH₃)CH₂—), and thelike.

“Aryl” refers to an unsaturated aromatic carbocyclic group having asingle ring (eg. phenyl) or multiple condensed rings (eg. naphthyl oranthryl), preferably having from 6 to 14 carbon atoms. Examples of arylgroups include phenyl, naphthyl and the like.

“Arylene” refers to a divalent aryl group wherein the aryl group is asdescribed above.

“Aryloxy” refers to the group aryl-O— wherein the aryl group is asdescribed above.

“Arylalkyl” refers to -alkylene-aryl groups preferably having from 1 to10 carbon atoms in the alkylene moiety and from 6 to 10 carbon atoms inthe aryl moiety. Such arylalkyl groups are exemplified by benzyl,phenethyl and the like.

“Arylalkoxy” refers to the group arylalkyl-O— wherein the arylalkylgroup are as described above. Such arylalkoxy groups are exemplified bybenzyloxy and the like.

“Alkoxy” refers to the group alkyl-O— where the alkyl group is asdescribed above. Examples include, methoxy, ethoxy, n-propoxy,iso-propoxy, n-butoxy, tert-butoxy, sec-butoxy, n-pentoxy, n-hexoxy,1,2-dimethylbutoxy, and the like.

“Alkenyl” refers to a monovalent alkenyl group which may be straightchained or branched and preferably have from 2 to 10 carbon atoms andmore preferably 2 to 6 carbon atoms and have at least 1 and preferablyfrom 1-2, carbon to carbon, double bonds. Examples include ethenyl(—CH═CH₂), n-propenyl (—CH₂CH═CH₂), iso-propenyl (—C(CH₃)═CH₂),but-2-enyl (—CH₂CH═CHCH₃), and the like.

“Alkenyloxy” refers to the group alkenyl-O— wherein the alkenyl group isas described above.

“Alkenylene” refers to divalent alkenyl groups preferably having from 2to 8 carbon atoms and more preferably 2 to 6 carbon atoms. Examplesinclude ethenylene (—CH═CH—), and the propenylene isomers (e.g.,—CH₂CH═CH— and —C(CH₃)═CH—), and the like.

“Alkynyl” refers to alkynyl groups preferably having from 2 to 10 carbonatoms and more preferably 2 to 6 carbon atoms and having at least 1, andpreferably from 1-2, carbon to carbon, triple bonds. Examples of alkynylgroups include ethynyl (—C≡CH), propargyl (—CH₂C≡CH), pent-2-ynyl(—CH₂C≡CCH₂—CH₃), and the like.

“Alkynyloxy” refers to the group alkynyl-O— wherein the alkynyl groupsis as described above.

“Alkynylene” refers to the divalent alkynyl groups preferably havingfrom 2 to 8 carbon atoms and more preferably 2 to 6 carbon atoms.Examples include ethynylene (—C≡C—), propynylene (—CH₂—C≡C—), and thelike.

“Acyl” refers to groups H—C(O)—, alkyl-C(O)—, cycloalkyl-C(O)—,aryl-C(O)—, heteroaryl-C(O)— and heterocyclyl-C(O)—, where alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl are as described herein.

“Oxyacyl” refers to groups HOC(O)—, alkyl-OC(O)—, cycloalkyl-OC(O)—,aryl-OC(O)—, heteroaryl-OC(O)—, and heterocyclyl-OC(O)—, where alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl are as described herein.

“Amino” refers to the group —NR″R″ where each R″ is independentlyhydrogen, alkyl, cycloalkyl, aryl, heteroaryl, and heterocyclyl andwhere each of alkyl, cycloalkyl, aryl, heteroaryl and heterocyclyl is asdescribed herein.

“Aminoacyl” refers to the group —C(O)NR″R″ where each R″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl and where each of alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl is as described herein.

“Acylamino” refers to the group —NR″C(O)R″ where each R″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl and where each of alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Acyloxy” refers to the groups —OC(O)-alkyl, —OC(O)-aryl,—C(O)O-heteroaryl, and —C(O)O-heterocyclyl where alkyl, aryl, heteroaryland heterocyclyl are as described herein.

“Aminoacyloxy” refers to the groups —OC(O)NR″-alkyl, —OC(O)NR″-aryl,—OC(O)NR″-heteroaryl, and —OC(O)NR″-heterocyclyl where R″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl and where each of alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl is as described herein.

“Oxyacylamino” refers to the groups —NR″C(O)O-alkyl, —NR″C(O)O-aryl,—NR″C(O)O-heteroaryl, and NR″C(O)O-heterocyclyl where R″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl and where each of alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl is as described herein.

“Oxyacyloxy” refers to the groups —OC(O)O-alkyl, —O—C(O)O-aryl,—OC(O)O-heteroaryl, and —OC(O)O-heterocyclyl where alkyl, cycloalkyl,aryl, heteroaryl, and heterocyclyl are as described herein.

“Acylimino” refers to the groups —C(NR″)—R″ where each R″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl and where each of alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Acyliminoxy” refers to the groups —O—C(NR″)—R″ where each R″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl and where each of alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Oxyacylimino” refers to the groups —C(NR″)—OR″ where each R″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl and where each of alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Cycloalkyl” refers to cyclic alkyl groups having a single cyclic ringor multiple condensed rings, preferably incorporating 3 to 11 carbonatoms. Such cycloalkyl groups include, by way of example, single ringstructures such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cyclooctyl, and the like, or multiple ring structures such asadamantanyl, indanyl, 1,2,3,4-tetrahydronapthalenyl and the like.

“Cycloalkenyl” refers to cyclic alkenyl groups having a single cyclicring or multiple condensed rings, and at least one point of internalunsaturation, preferably incorporating 4 to 11 carbon atoms. Examples ofsuitable cycloalkenyl groups include, for instance, cyclobut-2-enyl,cyclopent-3-enyl, cyclohex-4-enyl, cyclooct-3-enyl, indenyl and thelike.

“Halo” or “halogen” refers to fluoro, chloro, bromo and iodo.

“Heteroaryl” refers to a monovalent aromatic heterocyclic group whichfulfils the Hückel criteria for aromaticity (ie. contains 4n+2πelectrons) and preferably has from 2 to 10 carbon atoms and 1 to 4heteroatoms selected from oxygen, nitrogen, selenium, and sulfur withinthe ring (and includes oxides of sulfur, selenium and nitrogen). Suchheteroaryl groups can have a single ring (eg. pyridyl, pyrrolyl orN-oxides thereof or furyl) or multiple condensed rings (eg. indolizinyl,benzoimidazolyl, coumarinyl, quinolinyl, isoquinolinyl or benzothienyl).It will be understood that where, for instance, R₂ or R′ is anoptionally substituted heteroaryl which has one or more ringheteroatoms, the heteroaryl group can be connected to the core moleculeof the compounds of the present invention, through a C—C or C-heteroatombond, in particular a C—N bond.

“Heterocyclyl” refers to a monovalent saturated or unsaturated grouphaving a single ring or multiple condensed rings, preferably from 1 to 8carbon atoms and from 1 to 4 hetero atoms selected from nitrogen,sulfur, oxygen, selenium or phosphorous within the ring. The mostpreferred heteroatom is nitrogen. It will be understood that where, forinstance, R₂ or R′ is an optionally substituted heterocyclyl which hasone or more ring heteroatoms, the heterocyclyl group can be connected tothe core molecule of the compounds of the present invention, through aC—C or C-heteroatom bond, in particular a C—N bond.

Examples of heterocyclyl and heteroaryl groups include, but are notlimited to, oxazole, pyrrole, imidazole, pyrazole, pyridine, pyrazine,pyrimidine, pyridazine, indolizine, isoindole, indole, indazole, purine,quinolizine, isoquinoline, quinoline, phthalazine, naphthylpyridine,quinoxaline, quinazoline, cinnoline, pteridine, carbazole, carboline,phenanthridine, acridine, phenanthroline, isothiazole, phenazine,isoxazole, isothiazole, phenoxazine, phenothiazine, imidazolidine,imidazoline, piperidine, piperazine, indoline, phthalimide,1,2,3,4-tetrahydroisoquinoline, 4,5,6,7-tetrahydrobenzo[b]thiophene,thiazole, thiadiazoles, oxadiazole, oxatriazole, tetrazole,thiazolidine, thiophene, benzo[b]thiophene, morpholino, piperidinyl,pyrrolidine, tetrahydrofuranyl, triazole, and the like.

“Heteroarylene” refers to a divalent heteroaryl group wherein theheteroaryl group is as described above.

“Heterocyclylene” refers to a divalent heterocyclyl group wherein theheterocyclyl group is as described above.

“Thio” refers to groups H—S—, alkyl-S—, cycloalkyl-S—, aryl-S—,heteroaryl-S—, and heterocyclyl-S—, where alkyl, cycloalkyl, aryl,heteroaryl and heterocyclyl are as described herein.

“Thioacyl” refers to groups H—C(S)—, alkyl-C(S)—, cycloalkyl-C(S)—,aryl-C(S)—, heteroaryl-C(S)—, and heterocyclyl-C(S)—, where alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl are as described herein.

“Oxythioacyl” refers to groups HO—C(S)—, alkylO—C(S)—,cycloalkylO—C(S)—, arylO—C(S)—, heteroarylO—C(S)—, andheterocyclylO—C(S)—, where alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl are as described herein.

“Oxythioacyloxy” refers to groups HO—C(S)—O—, alkylO—C(S)—O—,cycloalkylO—C(S)—O—, arylO—C(S)—O—, heteroarylO—C(S)—O—, andheterocyclylO—C(S)—O—, where alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl are as described herein.

“Phosphorylamino” refers to the groups —NR″—P(O)(R′″)(OR′″) where R″represents H, alkyl, cycloalkyl, alkenyl, or aryl, R′″ represents OR″″or is hydroxy or amino and R″″ is alkyl, cycloalkyl, aryl or arylalkyl,where alkyl, amino, alkenyl, aryl, cycloalkyl, and arylalkyl are asdescribed herein.

“Thioacyloxy” refers to groups H—C(S)—O—, alkyl-C(S)—O—,cycloalkyl-C(S)-—O—, aryl-C(S)—O—, heteroaryl-C(S)—O—, andheterocyclyl-C(S)—O—, where alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Sulfinyl” refers to groups H—S(O)—, alkyl-S(O)—, cycloalkyl-S(O)—,aryl-S(O)—, heteroaryl-S(O)—, and heterocyclyl-S(O)—, where alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl are as described herein.

“Sulfonyl” refers to groups H—S(O)₂—, alkyl-S(O)₂—, cycloalkyl-S(O)₂—,aryl-S(O)₂—, heteroaryl-S(O)₂—, and heterocyclyl-S(O)₂—, where alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl are as described herein.

“Sulfinylamino” refers to groups H—S(O)—NR″-, alkyl-S(O)—NR″-,cycloalkyl-S(O)—NR″-, aryl-S(O)—NR″-, heteroaryl-S(O)—NR″-, andheterocyclyl-S(O)—NR″-, where R″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl and where each of alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl is as described herein.

“Sulfonylamino” refers to groups H—S(O)₂—NR″—, alkyl-S(O)₂—NR″—,cycloalkyl-S(O)₂—NR″—, aryl-S(O)₂—NR″—, heteroaryl-S(O)₂—NR″—, andheterocyclyl-S(O)₂—NR″—, where R″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl and where each of alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl is as described herein.

“Oxysulfinylamino” refers to groups HO—S(O)—NR″—, alkylO-S(O)—NR″—,cycloalkylO-S(O)—NR″—, arylO—S(O)—NR″—, heteroarylO—S(O)—NR″—, andheterocyclylO—S(O)—NR″—, where R″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl and where each of alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl is as described herein.

“Oxysulfonylamino” refers to groups HO—S(O)₂—NR″—, alkylO—S(O)₂—NR″—,cycloalkylO—S(O)₂—NR″—, arylO—S(O)₂—NR″—, heteroarylO—S(O)₂—NR″—, andheterocyclylO—S(O)₂—NR″—, where R″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl and where each of alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl is as described herein.

“Aminothioacyl” refers to groups R″R″N—C(S)—, where each R″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclic and where each of alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl is as described herein.

“Thioacylamino” refers to groups H—C(S)—NR″—, alkyl-C(S)—NR″—,cycloalkyl-C(S)—NR″—, aryl-C(S)—NR″—, heteroaryl-C(S)—NR″—, andheterocyclyl-C(S)—NR″-, where R″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl and where each of alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl is as described herein.

“Aminosulfinyl” refers to groups R″R″N—S(O)—, where each R″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclic and where each of alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl is as described herein.

“Aminosulfonyl” refers to groups R″R″N—S(O)₂—, where each R″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclic and where each of alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl is as described herein.

In this specification “optionally substituted” is taken to mean that agroup may or may not be further substituted or fused (so as to form acondensed polycyclic group) with one or more groups selected fromhydroxyl, acyl, alkyl, alkoxy, alkenyl, alkenyloxy, alkynyl, alkynyloxy,amino, aminoacyl, thio, arylalkyl, arylalkoxy, aryl, aryloxy, carboxyl,acylamino, cyano, halogen, nitro, phosphono, sulfo, phosphorylamino,phosphinyl, heteroaryl, heteroaryloxy, heterocyclyl, heterocyclyloxy,oxyacyl, oxime, oxime ether, hydrazone, oxyacylamino, oxysulfonylamino,aminoacyloxy, trihalomethyl, trialkylsilyl, pentafluoroethyl,trifluoromethoxy, difluoromethoxy, trifluoromethanethio,trifluoroethenyl, mono- and di-alkylamino, mono- and di-(substitutedalkyl)amino, mono- and di-arylamino, mono- and di-heteroarylamino, mono-and di-heterocyclyl amino, and unsymmetric di-substituted amines havingdifferent substituents selected from alkyl, aryl, heteroaryl andheterocyclyl, and the like, and may also include a bond to a solidsupport material, (for example, substituted onto a polymer resin). Forinstance, an “optionally substituted amino” group may include amino acidand peptide residues.

In a preferred embodiment two of A, E or D are N and the other is CR′.

Accordingly, preferred compounds of formula (I) are represented byformulae (Ia), (Ib), and (Ic):

Where R, R₁, R₂, R′, Y and X are as described above for compounds offormula (I).

In a more preferred embodiment only one of A, E and D is N and the othertwo independently CR′.

Accordingly, more preferred compounds are represented by formulae (Id),(Ie) and (If):

Where R, R₁, R₂, R′, Y and X are as described above for compounds offormula (I).

In the above embodiments R′ in CR′ includes the following groups:

-   hydrogen, halogen, cyano, nitro, and amino-   alkyl group, preferably methyl and ethyl;-   substituted alkyl group, preferably 1-hydroxyethyl, 1-thioethyl,    methoxyiminomethyl, ethoxyiminomethyl, 1-(hydroxyimino)ethyl,    1-(hydroxyimino)propyl, 1-hydrazinoethyl, 1-hydrazinopropyl,    hydroxyiminomethyl, 2-oxopropyl, 2-oxobutyl, 3-oxobutyl,    3-oxopentyl, nitromethyl, 1-nitromethyl, and 2-nitroethyl;-   aryl group, preferably phenyl and napthyl;-   substituted aryl group, preferably halophenyl, aminophenyl,    carboxyphenyl, hydroxyphenyl, cyanophenyl, nitrophenyl,    trihaloalkylphenyl, and alkylphenyl.-   acyl group, preferably formyl acetyl, propionyl, benzoyl (optionally    substituted with methyl, methoxy, halogen, nitro, trifluoromethyl or    cyano);-   alkoxy group, preferably methoxy and ethoxy;-   oxyacyl group, preferably methoxycarbonyl, ethoxycarbonyl,    propoxycarbonyl, butyloxycarbonyl, isobutyloxycarbonyl;-   acyloxy group, preferably acetoxy and propioxy;-   substituted arylalkyl group, preferably 1-hydroxybenzyl, and    1-thiobenzyl;-   sulfinyl group, preferably methylsulfinyl, ethylsulfinyl, benzene    sulfinyl (optionally substituted with methyl, methoxy, halogen,    nitro, trifluoromethane or cyano), methoxysulfinyl, ethoxysulfinyl;-   sulfonyl group, preferably methylsulfonyl, ethylsulfonyl,    benzenesulfonyl (optionally substituted with methyl, methoxy,    halogen, nitro, trifluoromethane or cyano), methoxycarbo,    trifluoromethane;-   oxyacylamino group, preferably methoxycarbonylamido, and    ethoxycarbonyl amido;-   oxythioacyl group, preferably methoxythiocarbonyl and    ethoxythiocarbonyl;-   thioacyloxy group, preferably thionoacetoxy and thionopropionoxy;-   sulphinylamino group, preferably methylsulfinylamino,    ethylsulfinylamino, and benzenesulfinylamino (optionally substituted    with methyl, methoxy, halogen, nitro, trifluoromethane or cyano);-   amino group, preferably N-methylamino, and N,N′-dimethylamino;-   substituted amino groups, preferably residues of L-valine, D-valine,    L-alanine, D-alanine, aspartic acid, and alanylserine;-   sulphonylamino group, preferably methylsulfonylamino,    ethylsulfonylamino and benzene sulfonylamino (optionally substituted    with methyl, methoxy, halogen, nitro, trifluoromethane or cyano);-   substituted thio group, preferably alkylthio;-   oxysulfinylamino group, preferably methoxysulfinylamino and    ethoxysulfinylamino;-   oxysulfonylamino group, preferably methoxysulfonylamino and    ethoxysulfonylamino;-   optionally substituted alkenyl group, preferably, 1-propenyl, vinyl,    nitrovinyl, cyano vinyl, or trifluorovinyl and styryl (optionally    substituted with methyl, methoxy, halogen, nitro, trifluoromethane    or cyano); and-   alkynyl group, preferably 1-propynyl, ethynyl or    trimethylsilylethynyl.

More preferably, where present, CR′ is CH.

In a preferred embodiment Y is NR³R⁴. In this embodiment preferably oneof R₃ and R₄ is H and the other is selected from optionally substitutedalkyl, optionally substituted aryl, optionally substituted C₃₋₇cycloalkyl, optionally substituted heteroaryl, or optionally substitutedheterocyclyl. In another preferred embodiment both R₃ and R₄ are eachindependently selected from optionally substituted C₁₋₃ alkyl.

In a further preferred embodiment Y is NR³R⁴ where R₃ and R₄ togetherwith the N-atom represent an optionally substituted N-containingheteroaryl or optionally substituted N-containing heterocyclyl.

Accordingly, in an even more preferred embodiment the compounds of thepresent invention are represented by formula (I′) or salts thereof

-   where A, E, and D are independently selected from CR′ (where R′ is    selected from H, carboxyl, cyano, dihalomethoxy, halogen, hydroxy,    nitro, pentahaloethyl, phosphono, phosphorylamino, phosphinyl,    sulfo, trihaloethenyl, trihalomethanethio, trihalomethyl,    trihalomethoxy, optionally substituted acyl, optionally substituted    acylamino, optionally substituted acylimino, optionally substituted    acyliminoxy, optionally substituted acyloxy, optionally substituted    arylalkyl, optionally substituted arylalkoxy, optionally substituted    alkenyl, optionally substituted alkenyloxy, optionally substituted    alkoxy, optionally substituted alkyl, optionally substituted    alkynyl, optionally substituted alkynyloxy, optionally substituted    amino, optionally substituted aminoacyl, optionally substituted    aminoacyloxy, optionally substituted aminosulfonyl, optionally    substituted aminothioacyl, optionally substituted aryl, optionally    substituted arylamino, optionally substituted aryloxy, optionally    substituted cycloalkenyl, optionally substituted cycloalkyl,    optionally substituted heteroaryl, optionally substituted    heterocyclyl, optionally substituted oxyacyl, optionally substituted    oxyacylamino, optionally substituted oxyacyloxy, optionally    substituted oxyacylimino, optionally substituted oxysulfinylamino,    optionally substituted oxysulfonylamino, optionally substituted    oxythioacyl, optionally substituted oxythioacyloxy, optionally    substituted sulfinyl, optionally substituted sulfinylamino,    optionally substituted sulfonyl, optionally substituted    sulphonylamino, optionally substituted thio, optionally substituted    thioacyl, and optionally substituted thioacylamino) or N, and    wherein at least one of A, E and D is N;    -   X represents O or NR″ (where R″ is selected from H, optionally        substituted alkyl, optionally substituted aryl, optionally        substituted cycloalkyl, optionally substituted acyl, optionally        substituted alkenyl, optionally substituted heterocyclyl,        optionally substituted heterocyclyl, optionally substituted        heteroaryl, optionally substituted oxysulfinyl, optionally        substituted oxysulfonyl, and optionally substituted sulfinyl,        optionally substituted sulfonyl);    -   R represents H or optionally substituted alkyl;    -   R₁ represents optionally substituted cycloalkyl, optionally        substituted alkyl, optionally substituted acyl, optionally        substituted aryl, optionally substituted heterocyclyl, or        optionally substituted heteroaryl;    -   R₂ represents H, optionally substituted cycloalkyl, optionally        substituted alkyl, optionally substituted acyl, optionally        substituted aryl, optionally substituted alkenyl, optionally        substituted heterocyclyl, optionally substituted heteroaryl,        optionally substituted oxysulfinyl, optionally substituted        oxysulfonyl, optionally substituted sulfinyl, or optionally        substituted sulfonyl; and    -   Q represents an optionally substituted N-containing heterocyclyl        or an optionally substituted N-containing heteroaryl.

In a preferred embodiment two of A, E and D are N and the other CR′.Accordingly, preferred compounds of formula (I′) are represented byformulae (I′a), (I′b), and (I′c):

where R, R₁, Q, R₂, R′ and X are as defined above.

In a more preferred embodiment only one of A, E, and D is N and theother two independently CR′. Accordingly, more preferred compounds arerepresented by formulae (I′d), (I′e), and (I′f):

where R, R₁, R₂, Q, R′ and X are as defined above.

Preferably, and in respect of compounds of formula (I′), Q representsoptionally substituted N-containing heterocyclyl. More preferably, Qrepresents an N-containing heterocyclyl selected from morpholinyl,piperidyl, piperazinyl, pyrrolidinyl, pyrazolinyl, pyrazolidinyl,imidazolinyl or indolinyl. Most preferably Q represents morpholinyl.

For the compounds of formulae (I) and (I′) preferably X is NR″ where R″is selected from hydrogen, C₁₋₃ alkyl, benzyl, or acetyl. Morepreferably X is NH.

For the compounds of formulae (I) and (I′) preferably R is H or C₁₋₆alkyl. More preferably R is hydrogen or methyl and even more preferablyhydrogen.

Preferably for compounds of formulae (I) and (I′), R₁ is selected fromoptionally substituted alkyl, optionally substituted cycloalkyl, oroptionally substituted cycloalkenyl. Preferred substitutents includeoptionally substituted acyl (for instance, optionally substitutedphenylacyl or optionally substituted alkyl acyl), optionally substitutedaryl, halogen, COOH, NH₂, mono or dialkyl amino or CF₃. More preferablyR₁ is benzofused C₅-C₇ cycloalkyl (wherein the benzene ring may beoptionally substituted). Most preferably, R₁ is indanyl or1,2,3,4-tetrahydronaphthalenyl.

For the compounds of formulae (I) and (I′) preferably R₂ is hydrogen,C₁₋₆ alkyl, benzyl or acetyl. More preferably R₂ is C₁₋₃ alkyl.

Accordingly, in an even more preferred embodiment the invention providescompounds of formulae (I′d), (I′e), and (I′f) or salts thereof, whereinQ represents N-containing heterocyclyl, X represents NR″ (where R″ isselected from hydrogen, C₁₋₃ alkyl, benzyl or acetyl), R is hydrogen, R₁represents optionally substituted cycloalkyl or optionally substitutedcycloalkenyl, R₂ represents C₁₋₃ alkyl and each R′ is hydrogen.

The compounds of the present invention can be prepared according toScheme 1 below:

In the above Scheme, preferably only one of A, E, or D is N.

As shown in Scheme 1 an amino substituted N-containing heteroaryl (eg a2-substituted-5-amino-pyridine) may be heated in the presence of adiethyl ethoxymethylene malonate in a suitable solvent (eg diethylether) to afford the desired diethyl aminomethylene malonate.

This product may then be cyclised at temperatures above 200° C. (forinstance in diphenyl ether) to afford the corresponding ring closedproduct (where Y is OEt). Hydrolysis of the ethyl ester under standardconditions may afford the corresponding carboxylic acid. Alternativelywhere it is desired to make compounds where R₂ is other than H, the ringclosed product may be reacted with a suitable electrophilic group (eg.alkylation with an alkylhalide) under standard conditions.

Coupling of the acid with HNR₄R₃ may be achieved under typical peptidecoupling conditions. For example, the carboxylic acid can be initiallyconverted to an activated ester with ethyl chloroformate or HBTU in thepresence of a suitable non-nucleophilic base (eg triethylamine, Hünigsbase, etc).

Alternatively other groups where Y is OR′″ may be produced by standardester forming methodology with an alcohol (R′″OH) and suitable acid.

Another approach to the compounds of the present invention is depictedin Scheme 2:

As shown in Scheme 2 a carboxy-substituted N-containing heteroaryl (eg a2,5-disubstituted nicotinic acid) may be converted to the malonate esterby reaction with thionyl chloride and potassium ethyl malonate understandard conditions. The L group depicted in Scheme 2 represents anysuitable leaving group which may be halogen, methoxy, tosylate,mesylate, etc. The malonate ester may be reacted withtriethylorthoformate in acetic acid followed by the addition of anucleophilic amine (HNR₂) to afford the ethylene amine which may besubsequently cyclised or be promoted to cyclise (eg in the presence of amild base (eg K₂CO₃)) to afford the ring closed product. Addition of theXR₁ group may be accomplished by nucleophilic substitution chemistrywith an effective nucleophilie eg ^({circle around (−)})NHR₁ or^({circle around (−)})OR₁ or may be introduced using palladium catalysedcoupling chemistry.

Accordingly, Z may be an oxygen based leaving group (or precursorthereof) such as a tosylate or mesylate, or a halogen for instance, Cl,Br, or I.

In Scheme 2 Z may alternatively be NO₂. In the final stages of thesynthesis (and preferably after the ring closure step) the NO₂ group maybe reduced to NH₂ with the use of, for instance, Raney nickel/H₂. Thecorresponding NH₂ group may be reacted with RL′ (L′ is a leaving group)to produce compounds where —XR₁ is —NHR₁.

It would be appreciated then that the introduction of the X—R₁ group maytake place at any convenient stage during the synthetic process and thatthis applies to both the strategies depicted in Schemes 1 and 2.

The preparation of di- and tri-substituted N-containing heteroaryls asstarting materials in the above synthetic procedures may be accomplishedusing conventional chemistry (see for instance, D. T. Davies, AromaticHeterocyclic Chemistry, 1993, Oxford Press, New York). Many suchstarting compounds have also been reported in the literature.

Other compounds of formulae I and I′ can be prepared by the addition,removal or modification of existing substituents. This could be achievedby using standard techniques for functional group inter-conversion thatare well known in the industry, such as those described in“Comprehensive organic transformations: a guide to functional grouppreparations” by Larock R. C., New York, VCH Publishers, Inc. 1989.

Examples of functional group inter-conversions are: —C(O)NR*R** from—CO₂CH₃ by heating with or without catalytic metal cyanide, e.g. NaCN,and HNR*R** in CH₃OH; —OC(O)R from —OH with e.g., ClC(O)R in pyridine;—NC(S)NR*R** from —NHR with an alkylisothiocyanate or thiocyanic acid;—NRC(O)OR* from —NHR with alkyl chloroformate; —NRC(O)NR*R** from —NHRby treatment with an isocyanate, e.g. HN═C═O or RN═C═O; —NRC(O)R* from—NHR by treatment with ClC(O)R* in pyridine; —C(═NR)NR*R** from—C(NR*R**)SR with H₃NR⁺OAc⁻ by heating in alcohol; —C(NR*R**)SR from—C(S)NR*R** with R—I in an inert solvent, e.g. acetone; —C(S)NR*R**(where R* or R** is not hydrogen) from —C(S)NH₂ with HNR*R**;—C(═NCN)—NR*R** from —C(═NR*R**)—SR with NH₂CN by heating in anhydrousalcohol, alternatively from —C(═NH)—NR*R** by treatment with BrCN andNaOEt in EtOH; —NR—C(═NCN)SR from —NHR* by treatment with (RS)₂C═NCN;—NR**SO₂R from —NHR* by treatment with ClSO₂R by heating in pyridine;—NR*C(S)R from —NR*C(O)R by treatment with Lawesson's reagent[2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide];—NRSO₂CF₃ from —NHR with triflic anhydride and base, —CH(NH₂)CHO from—CH(NH₂)C(O)OR* with Na(Hg) and HCl/EtOH; —CH₂C(O)OH from —C(O)OH bytreatment with SOCl₂ then CH₂N₂ then H₂O/Ag₂O; —C(O)OH from —CH₂C(O)OCH₃by treatment with PhMgX/HX then acetic anhydride then CrO₃; R—OC(O)R*from RC(O)R* by R**CO₃H; —CCH₂OH from —C(O)OR* with Na/R*OH; —CHCH₂ from—CH₂CH₂OH by the Chugaev reaction; —NH₂ from —C(O)OH by the Curtiusreaction; —NH₂ from —C(O)NHOH with TsCl/base then H₂O; —CHC(O)CHR from—CHCHOHCHR by using the Dess-Martin Periodinane regent orCrO₃/aqH₂SO₄/acetone; —C₆H₅CHO from —C₆H₅CH₃ with CrO₂Cl₂; —CHO from —CNwith SnCl₂/HCl; —CN from —C(O)NHR with PCl₅; —CH₂R from —C(O)R withN₂H₄/KOH.

During the reactions described above a number of the moieties may needto be protected. Suitable protecting groups are well known in industryand have been described in many references such as Protecting Groups inOrganic Synthesis, Greene T W, Wiley-Interscience, New York, 1981.

Without wanting to be bound by theory it is believed that the compoundsof the present invention are GABA_(A) receptor agonists which interactpreferentially or more favourably with the α2 and/or α3 subunit thanwith α1, although their effects may be mediated through interaction withother biomolecules.

The compounds of the present invention may be used in the treatment of avariety of disorders of the central nervous system.

Such disorders include anxiety disorders, such as panic disorder with orwithout agoraphobia, agoraphobia without history of panic disorder,animal and other phobias including social phobias, obsessive-compulsivedisorder, stress disorders including post-traumatic and acute stressdisorder, and generalized or substance-induced anxiety disorder;neuroses; convulsions; migraine; depressive or bipolar disorders, forexample single-episode or recurrent major depressive disorder, dysthymicdisorder, bipolar I and bipolar II manic disorders, and cyclothymicdisorder; psychotic disorders including schizophrenia; neurodegenerationarising from cerebral ischemia; attention deficit hyperactivitydisorder; Tourette's syndrome; speech disorders, including stuttering;and disorders of circadian rhythm, e.g. in subjects suffering from theeffects of jet lag or shift work.

Further disorders for which compounds of the invention may be of benefitinclude pain and nociception; emesis, including acute, delayed andanticipatory emesis, in particular emesis induced by chemotherapy orradiation, as well as motion sickness, and post-operative nausea andvomiting; eating disorders including anorexia nervosa and bulimianervosa; premenstrual syndrome; muscle spasm or spasticity, e.g. inparaplegic patients; hearing disorders, including tinnitus andage-related hearing impairment; urinary incontinence; and the effects ofsubstance abuse or dependency, including alcohol withdrawal. Compoundsof the invention may be beneficial in enhancing cognition, for examplein subjects suffering from dementing conditions such as Alzheimer'sdisease; and may also be effective as pre-medication prior toanaesthesia or minor procedures such as endoscopy, including gastricendoscopy.

The invention also provides for the use of a compound of formulae (I)and (I′) in the manufacture of a medicament for treating disorders ofthe central nervous system.

There is also provided a method of treatment of disorders of the centralnervous system comprising the administration of an effective amount ofat least one compound of formula (I) or (I′) to a subject in needthereof.

The compounds of the invention may be particularly useful in combinationtherapy, eg. combining the treatment with other chemotherapeutictreatments (eg muscle relaxants, anticonvulants, hypnotics,anaesthetics, analgesics or other anxiolytics, etc).

It will be understood that the compounds of the invention can be used inthe treatment of any disease state which may be ameliorated bymodulation of the GABA_(A) receptor complex.

The compounds of the invention are administered to the subject in atreatment effective amount. As used herein, a treatment effective amountis intended to include at least partially attaining the desired effect,or delaying the onset of, or inhibiting the progression of, or haltingor reversing altogether the onset or progression of the particulardisease of condition being treated.

As used herein, the term “effective amount” relates to an amount ofcompound which, when administered according to a desired dosing regimen,provides the desired therapeutic activity. Dosing may occur at intervalsof minutes, hours, days, weeks, months or years or continuously over anyone of these periods. Suitable dosages lie within the range of about 0.1ng per kg of body weight to 1 g per kg of body weight per dosage. Thedosage may be in the range of 1 μg to 1 g per kg of body weight perdosage, such as is in the range of 1 mg to 1 g per kg of body weight perdosage. In one embodiment, the dosage may be in the range of 1 mg to 500mg per kg of body weight per dosage. In another embodiment, the dosagemay be in the range of 1 mg to 250 mg per kg of body weight per dosage.In yet another preferred embodiment, the dosage may be in the range of 1mg to 100 mg per kg of body weight per dosage, such as up to 50 mg perbody weight per dosage.

Suitable dosage amounts and dosing regimens can be determined by theattending physician and may depend on the particular condition beingtreated, the severity of the condition as well as the general age,health and weight of the subject.

The active ingredient may be administered in a single dose or a seriesof doses. While it is possible for the active ingredient to beadministered alone, it is preferable to present it as a composition,preferably as a pharmaceutical composition. The formulation of suchcompositions is well known to those skilled in the art. The compositionmay contain any suitable carriers, diluents or excipients. These includeall conventional solvents, dispersion media, fillers, solid carriers,coatings, antifungal and antibacterial agents, dermal penetrationagents, surfactants, isotonic and absorption agents and the like. Itwill be understood that the compositions of the invention may alsoinclude other supplementary physiologically active agents.

The carrier must be pharmaceutically “acceptable” in the sense of beingcompatible with the other ingredients of the composition and notinjurious to the subject. Compositions include those suitable for oral,rectal, nasal, topical (including buccal and sublingual), vaginal orparental (including subcutaneous, intramuscular, intravenous andintradermal) administration. The compositions may conveniently bepresented in unit dosage form and may be prepared by any methods wellknown in the art of pharmacy. Such methods include the step of bringinginto association the active ingredient with the carrier whichconstitutes one or more accessory ingredients. In general, thecompositions are prepared by uniformly and intimately bringing intoassociation the active ingredient with liquid carriers or finely dividedsolid carriers or both, and then if necessary shaping the product.

Compositions of the present invention suitable for oral administrationmay be presented as discrete units such as capsules, sachets or tabletseach containing a predetermined amount of the active ingredient; as apowder or granules; as a solution or a suspension in an aqueous ornon-aqueous liquid; or as an oil-in-water liquid emulsion or awater-in-oil liquid emulsion. The active ingredient may also bepresented as a bolus, electuary or paste.

A tablet may be made by compression or moulding, optionally with one ormore accessory ingredients. Compressed tablets may be prepared bycompressing in a suitable machine the active ingredient in afree-flowing form such as a powder or granules, optionally mixed with abinder (e.g inert diluent, preservative disintegrant (e.g. sodium starchglycolate, cross-linked polyvinyl pyrrolidone, cross-linked sodiumcarboxymethyl cellulose) surface-active or dispersing agent. Mouldedtablets may be made by moulding in a suitable machine a mixture of thepowdered compound moistened with an inert liquid diluent. The tabletsmay optionally be coated or scored and may be formulated so as toprovide slow or controlled release of the active ingredient thereinusing, for example, hydroxypropylmethyl cellulose in varying proportionsto provide the desired release profile. Tablets may optionally beprovided with an enteric coating, to provide release in parts of the gutother than the stomach.

Compositions suitable for topical administration in the mouth includelozenges comprising the active ingredient in a flavoured base, usuallysucrose and acacia or tragacanth gum; pastilles comprising the activeingredient in an inert basis such as gelatine and glycerin, or sucroseand acacia gum; and mouthwashes comprising the active ingredient in asuitable liquid carrier.

Compositions suitable for topical administration to the skin maycomprise the compounds dissolved or suspended in any suitable carrier orbase and may be in the form of lotions, gel, creams, pastes, ointmentsand the like. Suitable carriers include mineral oil, propylene glycol,polyoxyethylene, polyoxypropylene, emulsifying wax, sorbitanmonostearate, polysorbate 60, cetyl esters wax, cetearyl alcohol,2-octyldodecanol, benzyl alcohol and water. Transdermal patches may alsobe used to administer the compounds of the invention.

Compositions for rectal administration may be presented as a suppositorywith a suitable base comprising, for example, cocoa butter, glycerin,gelatine or polyethylene glycol.

Compositions suitable for vaginal administration may be presented aspessaries, tampons, creams, gels, pastes, foams or spray formulationscontaining in addition to the active ingredient such carriers as areknown in the art to be appropriate.

Compositions suitable for parenteral administration include aqueous andnon-aqueous isotonic sterile injection solutions which may containanti-oxidants, buffers, bactericides and solutes which render thecomposition isotonic with the blood of the intended recipient; andaqueous and non-aqueous sterile suspensions which may include suspendingagents and thickening agents. The compositions may be presented inunit-dose or multi-dose sealed containers, for example, ampoules andvials, and may be stored in a freeze-dried (lyophilised) conditionrequiring only the addition of the sterile liquid carrier, for examplewater for injections, immediately prior to use. Extemporaneous injectionsolutions and suspensions may be prepared from sterile powders, granulesand tablets of the kind previously described.

Preferred unit dosage compositions are those containing a daily dose orunit, daily sub-dose, as herein above described, or an appropriatefraction thereof, of the active ingredient.

It should be understood that in addition to the active ingredientsparticularly mentioned above, the compositions of this invention mayinclude other agents conventional in the art having regard to the typeof composition in question, for example, those suitable for oraladministration may include such further agents as binders, sweeteners,thickeners, flavouring agents disintegrating agents, coating agents,preservatives, lubricants and/or time delay agents. Suitable sweetenersinclude sucrose, lactose, glucose, aspartame or saccharine. Suitabledisintegrating agents include cornstarch, methylcellulose,polyvinylpyrrolidone, xanthan gum, bentonite, alginic acid or agar.Suitable flavouring agents include peppermint oil, oil of wintergreen,cherry, orange or raspberry flavouring. Suitable coating agents includepolymers or copolymers of acrylic acid and/or methacrylic acid and/ortheir esters, waxes, fatty alcohols, zein, shellac or gluten. Suitablepreservatives include sodium benzoate, vitamin E, alpha-tocopherol,ascorbic acid, methyl paraben, propyl paraben or sodium bisulphite.Suitable lubricants include magnesium stearate, stearic acid, sodiumoleate, sodium chloride or talc. Suitable time delay agents includeglyceryl monostearate or glyceryl distearate.

Preferably, the compounds of the present invention may be administeredto a subject as a pharmaceutically acceptable salt. It will beappreciated however that non-pharmaceutically acceptable salts also fallwithin the scope of the present invention since these may be useful asintermediates in the preparation of pharmaceutically acceptable salts.Suitable pharmaceutically acceptable salts include, but are not limitedto salts of pharmaceutically acceptable inorganic acids such ashydrochloric, sulphuric, phosphoric, nitric, carbonic, boric, sulfamic,and hydrobromic acids, or salts of pharmaceutically acceptable organicacids such as acetic, propionic, butyric, tartaric, maleic,hydroxymaleic, fumaric, maleic, citric, lactic, mucic, gluconic,benzoic, succinic, oxalic, phenylacetic, methanesulphonic,toluenesulphonic, benezenesulphonic, salicyclic sulphanilic, aspartic,glutamic, edetic, stearic, palmitic, oleic, lauric, pantothenic, tannic,ascorbic and valeric acids.

Base salts include, but are not limited to, those formed withpharmaceutically acceptable cations, such as sodium, potassium, lithium,calcium, magnesium, ammonium and alkylammonium. In particular, thepresent invention includes within its scope cationic salts eg sodium orpotassium salts, or alkyl esters (eg methyl, ethyl) of the phosphategroup.

Basic nitrogen-containing groups may be quarternised with such agents aslower alkyl halide, such as methyl, ethyl, propyl, and butyl chlorides,bromides and iodides; dialkyl sulfates like dimethyl and diethylsulfate; and others.

It will be appreciated that any compound that is a prodrug of a compoundof formula (I) or (I′) is also within the scope and spirit of theinvention. The term “pro-drug” is used in its broadest sense andencompasses those derivatives that are converted in vivo to thecompounds of the invention. Such derivatives would readily occur tothose skilled in the art, and include, for example, compounds where afree hydroxy group (for instance at the CR′ position) is converted intoan ester, such as an acetate or phosphate ester, or where a free aminogroup is (for instance at the CR′ position) converted into an amide (eg.α-aminoacid amide). Procedures for esterifying, eg. acylating, thecompounds of the invention are well known in the art and may includetreatment of the compound with an appropriate carboxylic acid, anhydrideor chloride in the presence of a suitable catalyst or base. Aparticularly preferred prodrug is a disodium phosphate ester. Thedisodium phosphate ester may be prepared in accordance with themethodology described in Pettit, G. R., et al, Anticancer Drug Des.,1995, 10, 299.

The compounds of the invention may be in crystalline form either as thefree compounds or as solvates (e.g. hydrates) and it is intended thatboth forms are within the scope of the present invention. Methods ofsolvation are generally known within the art.

It will also be recognised that compounds of the invention may possessasymmetric centres and are therefore capable of existing in more thanone stereoisomeric form. The invention thus also relates to compounds insubstantially pure isomeric form at one or more asymmetric centres eg.,greater than about 90% ee, such as about 95% or 97% ee or greater than99% ee, as well as mixtures, including racemic mixtures, thereof. Suchisomers may be prepared by asymmetric synthesis, for example usingchiral intermediates, or mixtures may be resolved by conventionalmethods, eg., chromatography, or use of a resolving agent.

Furthermore, depending on the substitution pattern the compounds of thepresent invention may be capable of undergoing tautomerism. Accordingly,all possible tautomers of a compound of the present invention fallwithin the scope and spirit of the invention.

The synthetic methods and processes described herein to prepare thecompounds of the present invention are amenable to solid phase synthetictechniques and/or combinatorial chemistry to produce individualcompounds or libraries of compounds.

Traditionally, drug candidates have been synthesised individually, thisbeing a time consuming and laborious process if the synthetic sequencecontains even just a few steps and large numbers of compounds are to beevaluated for their biological activity. Combinatorial synthesis is anemerging technique for effecting the generation of large libraries ofmolecules and has been successfully exploited in the synthesis andevaluation of small organic libraries. These libraries and theirstarting substrates may exist as molecules in free solution orpreferably, linked to a solid support, for example, beads, pins,microtitre plates (wells) or microchips which can be polymeric, glass,silica or other suitable substrate. Chemical diversity can be achievedby either parallel or split (split and mix) syntheses wherein each stephas the potential to afford a multitude of compounds. Solution phaselibraries may be prepared via parallel syntheses wherein differentcompounds are synthesised in separate reaction vessels in parallel,often in an automated fashion. Alternatively, attachment of theindividual components employed in a synthetic sequence to an appropriatesolid phase support allows for the further creation of chemicaldiversity by utilising not only parallel synthesis but also splitsynthesis wherein the solid support containing the compounds prepared inthe prior step can be split into a number of batches, treated with theappropriate reagent and recombined.

The substrates can be attached to a solid support surface by any linkersknown in the art. The linkers may be any component capable of beingcleaved to release the substrate or final compound from the support.

Preferably, the solid support is a polymer support. Examples ofpolymeric supports currently used in solid phase synthesis include:alkenyl resins: eg. REM resins; BHA resins: eg. benzhydrylamine(polymer-bound hydrochloride, 2% crosslinked), benzhydryl chloride(polymer bound); Br-functionalised resins: eg. brominated PPOA resin,brominated Wang resin; Chloromethyl resins: eg. 4-methoxybenzhydrylchloride (polymer bound); CHO-functionalised resins: eg. indole resin,formylpolystyrene; Cl-functionalised resins: eg. Merrifield's resin,chloroacetyl (polymer bound); CO₂H-functionalised resins: eg.carboxypolystyrene; 1-functionalised resins: eg. 4-iodophenol (polymerbound); Janda Jels™; MBHA resins: eg. 4-methylbenzhydrylaminehydrochloride (polymer bound), 4-hydroxymethylbenzoic acid-4-methylbenzhydrylamine (polymer bound); Amine-functionalised resins: eg.(aminomethyl)polystyrene, PAL resin, Sieber amide resin; Nitrophenylcarbonate resins: eg. 4-nitrophenyl carbonate (polymer bound);OH-functionalised resins: eg. 4-benzyloxybenzyl alcohol (polymer bound);Hydroxy methyl resins: eg. benzyl alcohol (polymer bound); HMBA resin;Oxime resins; Rink acid resin; Triazine-based resin; Trityl amineresins; Trityl resins: eg. trityl-chloride (polymer bound),2-chlorotrityl alcohol, 1,3-diaminepropane trityl.

Thus, individual compounds or libraries of compounds can be synthesisedby initially attaching the first compound substrate to a solid supportsurface which can be performed by providing a plurality of solid supportsurfaces, suitably derivatising each of the surfaces with groups capableof reacting with either the compound substrate or a linker moietyattached thereto. The various support surfaces with the attached firstcompound substrate can then be subjected to various reaction conditionsand second compound substrates to provide a library of attachedcompounds, which may, if necessary, be reacted further with third andsubsequent compound substrates or varying reactions conditions.Attachment and detachment of substrates and products can be performedunder conditions similar to those as described in Johnson, M. G., etal., Tetrahedron, 1999, 55, 11641; Han Y., et al. Tetrahedron 1999, 55,11669; and Collini, M. D., et al., Tetrahedron Lett., 1997, 58, 7963.

Those skilled in the art will appreciate that the invention describedherein in susceptible to variations and modifications other than thosespecifically described. It is to be understood that the inventionincludes all such variations and modifications which fall within thespirit and scope. The invention also includes all of the steps,features, compositions and compounds referred to or indicated in thisspecification, individually or collectively, and any and allcombinations of any two or more of said steps or features.

Throughout this specification and the claims which follow, unless thecontext requires otherwise, the word “comprise”, and variations such as“comprises” and “comprising”, will be understood to imply the inclusionof a stated integer or step or group of integers or steps but not theexclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (orinformation derived from it), or to any matter which is known, is not,and should not be taken as an acknowledgment or admission or any form ofsuggestion that that prior publication (or information derived from it)or known matter forms part of the common general knowledge in the fieldof endeavour to which this specification relates.

Certain embodiments of the invention will now be described withreference to the following examples which are intended for the purposeof illustration only and are not intended to limit the scope of thegenerality hereinbefore described.

EXAMPLES

Synthetic Protocols

Example 1 Preparation of Morpholino6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxamide(Example 1)

a) 2-Hydroxy-5-nitro-nicotinic acid

To 2-hydroxy-nicotinic acid (3.6 mmol) in sulfuric acid (30% free SO₃, 2ml) was added sodium nitrate (7.2 mmol) portionwise over 20 min. Thesolution was allowed to stir for 20 h at room temperature. The solutionwas then poured onto ice-water and the precipitate that formed wasfiltered off, washed with water and dried in a vacuum oven to afford apale yellow solid (45%).

ESIMS: M−1: 183

¹H NMR (300 MHz, DMSO) δ 8.94 (1H, d, H-4), 8.67 (1H, d, H-6).

b) 2-Chloro-5-nitro-nicotinic acid

2-Hydroxy-5-nitro-nicotinic acid (2.7 mmol) in a mixture ofN,N-dimethylformamide (2.7 mmol) and thionyl chloride (5 ml) was heatedat 80° C. for 1 h. The mixture was allowed to cool and concentrated invacuo. To the resulting residue was added ice-water (20 ml) and withvigorous stirring a precipitate formed. The precipitate was filtered offand dried in a vacuum oven to give a white solid (68%).

ESIMS: M−1: 201

¹H NMR (300 MHz, DMSO) δ 9.30 (1H, d, H-4), 8.83 (1H, d, H-6).

c) 2-Methoxy-5-nitro-nicotinic acid

To 2-chloro-5-nitro-nicotinic acid (1.0 mmol) in methanol was added asolution of sodium methoxide in methanol (2.4 mmol, freshly preparedfrom sodium metal in methanol). The solution was refluxed for 2 h andthe mixture was allowed to cool and concentrated in vacuo. To theresulting residue was added 10% citric acid solution (20 ml) and thesolution extracted with ethyl acetate (20 ml). The organic layer wasdried (MgSO₄) and concentrated in vacuo. The residue was crystallisedfrom water to give a yellow-white solid (73%).

ESIMS M−1: 197

¹H NMR (300 MHz, DMSO) δ 9.30 (1H, d, H-4), 8.83 (1H, d, H-6), 4.05 (3H,s, OCH₃).

d) Preparation of Ethyl3-oxo-3-(5-nitro-2-methoxy-pyridin-3-yl)-propionate

2-Methoxy-5-nitro-nicotinic acid (36 mmol) and phosphorous pentachloride(72 mmol) were heated at 100° C. for 2 h. The excess reagent was removedin vacuo to give an oily residue.

To a solution of ethyl potassium malonate (75.6 mmol) and triethylamine(72 mmol) in acetonitrile (110 ml) was added magnesium chloride (90mmol) portionwise over 10 min. This solution was allowed to stir for 8 hat 35° C. To this solution was added dropwise a solution of the pyridylchloride (from above) in acetonitrile (15 ml) at 0° C. over 20 min. Thesolution was allowed to warm to room temperature and stirred for 20 h.To this solution was added diethyl ether (100 ml) and 1N hydrochloricacid solution until the pH 5-6 was reached. The two layers wereseparated and the organic layer was washed with water (100 ml). Theorganic layer was then dried (MgSO₄) and concentrated in vacuo. Theresulting residue was then subjected to column chromatography elutingwith dichloromethane to afford a clear oily liquid (78%). The NMRspectrum of this compound showed evidence of ketone-enol tautomerism.

ESIMS: M−1: 267

¹H NMR (300 MHz, DMSO) δ 9.17 (d, 0.6H), 9.05 (d, 0.4H), 8.96 (d, 0.4H),8.94 (d, 0.6H), 6.20 (s, 0.4H), 4.31-4.13 (m, 5H, OMe+OCH₂), 3.99 (s,1.2H), 1.33 (t, 3×0.4H), 1.22 (t, 3×0.6H)

Rf: 0.94 (95:5, dichloromethane:methanol)

e) Ethyl1-ethyl-1,4-dihydro-6-nitro-4-oxo-1,8-naphthyridine-3-carboxylate

The pyridyl malonate (18 mmol) and triethylorthoformate (23.4 mmol) inacetic anhydride (8 ml) were refluxed for 1 h. The solution was allowedto cool and the excess acetic anhydride was distilled off in vacuo. Tothe resulting residue in acetonitrile (40 ml) was added dropwiseethylamine (36 mmol) in diethyl ether (20 ml) and the solution wasallowed to stir for 5 h at room temperature. The solution was thenallowed to cool and was concentrated in vacuo. The residue was dissolvedin dichloromethane (60 ml) and washed with water (2×60 ml). The organiclayer was then dried (MgSO₄) and concentrated in vacuo. The resultingresidue was subjected to column chromatography eluting with 100%dichloromethane, and then 2% methanol/dichloromethane to give a whitesolid (78%).

ESIMS: M+1: 292

¹H NMR (300 MHz, CDCl₃) δ 9.50 (1H, d, H-5), 9.44 (1H, d, H-7), 8.66(1H, s, H-2), 4.53 (2H, q, OCH₂), 4.39 (2H, q, NCH₂), 1.51 (3H, t, OCH₂CH ₃), 1.40 (3H, t, NCH₂ CH ₃)

R_(f): 0.65 (95:5, dichloromethane:methanol)

f) Ethyl1-ethyl-1,4-dihydro-6-amino-4-oxo-1,8-naphthyridine-3-carboxylate

The naphthyridine (1.7 mmol) in N,N-dimethyl formamide (10 ml) washydrogenated over Raney nickel (0.17 mmol) for 4 h at rt. The mixturewas filtered through Celite and washed with tetrahydrofuran. Thefiltrate was evaporated to dryness. Crystallisation from ethanolobtained the residue as a pale yellow solid (67%).

ESIMS: M+1: 262

¹H NMR (300 MHz, DMSO) δ 8.43 (1H, s, H2), 7.49 (1H, d, J=9.0 Hz), 7.34(1H, s, NCH), 7.02 (1H, d, J=9.0 Hz, ArH), 5.50 (2H, s, NH₂), 4.28 (2H,q, J=7.0 Hz, OCH₂), 4.16 (2H, q, J=7.1 Hz, NCH₂), 1.31 (3H, t, J=7.0 Hz,OCH₂ CH ₃), 1.23 (3H, t, J=7.1 Hz, NCH₂ CH ₃)

R_(f): 0.40 (90:0, CH₂Cl₂:CH₃OH)

g) Ethyl6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate

A stirred solution of the naphthyridine (0.1 mmol), sodium sulfate (1.0mmol), 2-indanone (0.15 mmol) and AcOH (7.5 ml) in dichloroethane (30ml) under a nitrogen atmosphere was allowed to mature for 15 mins atroom temperature. Sodium triacetoxyborohydride (0.15 mmol) was thenadded in one portion and the solution was allowed to stir for 4 h at rt(the reaction was monitored by TLC). A second addition of sodium sulfate(1.0 mmol), 2-indanone (0.15 mmol) and sodium triacetoxyborohydride(0.15 mmol) and stirring overnight was required to drive the reaction tocompletion. The reaction mixture was quenched with 10% sodium hydrogencarbonate solution and dichloromethane added to dilute the solution. Theorganic layer was separated from the aqueous layer and the organic layerdried (MgSO₄). The organic layer was concentrated in vacuo and theresulting residue subjected to silica column chromatography,gradient-eluting with 100% dichloromethane and then 1%MeOH/dichloromethane to give an oily residue. The residue was trituratedusing diethyl ether and the solid was filtered off at the pump to afforda pale yellow solid (78%).

ESIMS: M+1: 378

¹H NMR (300 MHz, CDCl₃) δ 8.64 (1H, s, H-2), 8.30 (1H, d, H-5), 7.55(1H, d, H-7), 7.23-7.10 (4H, m, 4xArH), 6.69 (1H, d, NH), 4.41 (3H,q,OCH₂), 4.38-4.23 (1H, m, NCH), 4.17 (2H, q, NCH₂), 3.32 (2H, dd, CHCH₂), 2.81 (2H, dd, CHCH ₂), 1.32 (3H, t, OCH₂ CH ₃), 1.25 (3H, t, NCH₂ CH₃).

R_(f): 0.45 (95:5, CH₂Cl₂:CH₃OH)

h)6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylicacid

To the naphthyridine (0.29 mmol) in EtOH (2.5 mL) was added 2N NaOH inwater (12.5 mL) at room temperature. The solution was then allowed tostir for 2 h at 90° C. The organic solvent was then removed in vacuo andthe remaining aqueous solution was acidified with 10% citric acidsolution. The solid that formed was filtered off at the pump and washedwith water. This solid was then dried in a vacuum oven to obtain a paleyellow solid (90% yield).

ESIMS: M+1: 350

¹H NMR (300 MHz, DMSO-d₆) δ 8.96 (1H, s, H-2), 8.48 (1H, d, H-5), 7.55(1H, d, H-7), 7.25-7.12 (4H, m, 4xArH), 7.02 (1H, d, NH), 4.58 (2H, q,NCH₂), 4.36-4.31 (1H, m, NCH), 3.32 (2H, dd, CHCH ₂), 2.83 (2H, dd, CHCH₂), 1.36 (3H, t, NCH₂ CH ₃).

R_(f): 0.68 (90:10, CH₂Cl₂:CH₃OH)

i) Morpholino6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxamide

Trimethylaluminium (0.8 mmol, 2M in toluene) was added dropwise to astirred solution of morpholine (0.8 mmol) in dichloromethane (5 ml). Themixture was stirred for 15 mins and then the naphthyridine (0.4 mmol) indichloromethane (5 ml) was added. The mixture was then stirred for 20 hat 35° C. The mixture was cooled and then quenched by adding 2 Nhydrochloric acid (10 ml) dropwise. The organic layer was thenseparated, dried (MgSO₄) and concentrated in vacuo. The resultingresidue was triturated with diethyl ether to give a white solid (78%).

ESIMS: M+1: 419

¹H NMR (300 MHz, CDCl₃) δ 8.34 (1H, d, H-5), 8.23 (1H, s, H-2), 7.52(1H, d, H-7), 7.23-7.11 (4H, m, 4xArH), 6.61 (1H, d, NH), 4.38 (3H, q,NCH₂), 4.34-4.27 (1H, m, NCH), 3.36 (2H, dd, CHCH ₂), 1.31 (3H, t, NCH₂CH ₃)

R_(f): 0.31 (90:10, dichloromethane:methanol)

Example 2 Preparation of Morpholino6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxamide(Example 2)

a) N-(2,3-Dihydro-1H-inden-2-yl)-5-nitropyridin-2-amine

A mixture of 2-chloro-5-nitropyridine (4 g) andN,N-diisopropylethylamine (3 ml) was heated under reflux in dry ethanol(100 ml) for 2 h. The reaction mixture was cooled to 0° C., the solidwhich separated was filtered off washed with little cold ethanol, driedto give the product (6.25 g, 88%).

¹H NMR (300 MHz, CDCl₃) δ 8.98 (1H, s, H-6), 8.23 (1H, d, H-4),7.26-7.17 (4H, m, Ar), 6.43 (1H, d, H-3), 6.12 (1H, bs, NH), 4.71 (1H,bs, NCH), 3.44 (2H, dd, CHCH ₂), 2.93 (2H, dd CHCH ₂); and

ESIMS M+1: 256.

b) N²-(2,3-Dihydro-1H-inden-2-yl)pyridine-2,5-diamine & Diethyl2-((6-(2,3-dihydro-1H-inden-2-ylamino)pyridine-3-ylamino)methylene)malonate

A mixture of N-(2,3-dihydro-1H-inden-2-yl)-5-nitropyridin-2-amine (5.5g) and Raney Nickel (50 mg) was stirred in DMF (30 ml) under hydrogenovernight. The reaction mixture was filtered through celite and thesolvent removed in vacuo, giving as a residue crudeN²-(2,3-dihydro-1H-inden-2-yl)pyridine-2,5-diamine, which was on-reactedwithout further characterization other than ascertaining that thecompound was one spot by tlc with the expected molecular weight (M+1) of226.

A crude mixture of N²-(2,3-dihydro-1H-inden-2-yl)pyridine-2,5-diamine (5g) and diethyl ethoxymethylenemalonate (5.5 g) was heated under refluxin dry diethyl ether (50 ml) for 1 h. The reaction mixture was thencooled to room temperature, and solvent removed under reduced pressureand the remaining residue finally recrystallised from acetonitrile togive the diethyl2-((6-(2,3-dihydro-1H-inden-2-ylamino)pyridin-3-ylamino)methylene)malonate(6 g).

¹H NMR (300 MHz, DMSO-d₆) δ 10.58 (1H, d, 3-NHCH), 8.15 (1H, d, 3-NHCH),8.02 (1H, s, H-2), 7.45 (1H, dd, H-4), 7.20-7.10 (4H, m, Ar), 6.49 (1H,d, 2-NH), 4.51 (1H, m, 2-NHCH), 6.16-4.04 (4H, 2q, 2xOCH₂), 3.44 (2H,dd, CHCH ₂), 2.93 (2H, dd CHCH ₂), 1.24-1.16 (6H, 2t, OCH₂ CH ₃).

ESIMS: M+1: 396.

c) Ethyl6-(2,3-dihydro-1H-inden-2-yl)amino-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxylate

A solution of diethyl2-((6-(2,3-dihydro-1H-inden-2-ylamino)pyridin-3-ylamino)methylene)malonate(1.3 g) in dichloromethane (10 ml) was added very carefully intopre-heated (230° C.) diphenyl ether (20 ml) with stiffing and heatingwas continued with stiffing for another 20 min after addition had beencompleted. This was then allowed to cool to room temperature, petroleumether (200 ml) was added, and the solid which separated was filtered offdried to give the crude product (600 mg), which was on-reacted withoutfurther characterization other than ascertaining that the compound wasone spot by tlc with the expected molecular weight (M+1) of 350.

d) Ethyl6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxylate

A mixture of ethyl6-(2,3-dihydro-1H-inden-2-ylamino)-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxylate(600 mg), iodoethane (1 g) and potassium carbonate (600 mg) were heatedat 90° C. in DMF (20 ml) overnight. After a standard ethylacetate/aqueous work-up, the residue from the evaporated organic layer(crude cyclized ethyl ester), was heated at 80° C. in a mixture ofethanol (25 ml) and 2M NaOH (10 ml) for 2 h. This was then cooled toroom temperature, aq. HCl was added to adjust the pH to 5, at whichpoint the product precipitated and was filtered off, washed with water,and dried to give the crude product (−350 mg).

¹H NMR (300 MHz, DMSO-d₆) δ 8.78 (1H, s, H-2), 8.10 (1H, dd, H-8), 7.71(1H, d, H-7), 7.24-7.11 (4H, m, Ar), 7.06 (1H, d, NH), 4.75 (1H, m,NHCH), 4.46 (2H, q, NCH₂), 3.32 (2H, dd, CHCH ₂), 2.83 (2H, dd CHCH ₂),1.33 (3H, t, NCH₂ CH ₃); and

ESIMS: M+1: 350.

e) Morpholino6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxamide

A mixture of6-(2,3-dihydro-1H-inden-2-yl)amino-1-ethyl-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxylicacid (200 mg), HBTU (250 mg) and N,N-diisopropylethylamine (150 mg) indry DMF (1.5 ml) were stirred for 1 h at RT. Finally morpholine (100 mg)was added and the reaction mixture was stirred overnight. After astandard ethyl acetate/aqueous work-up, the residue from the evaporatedorganic layer was purified by passing through silica gel column usingacetone as a mobile phase to give the6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,5-naphthyridine-3-(˜150mg).

¹H NMR (300 MHz, DMSO-d₆) δ 8.00 (1H, s, H-2), 7.89 (1H, dd, H-8), 7.30(1H, d, H-7), 7.22-7.10 (4H, m, Ar), 6.93 (1H, d, NH), 4.75 (1H, m,NHCH), 4.23 (2H, q, NCH ₁), 3.56-3.27 (8H, bm, morpholino), (3.27 (2H,dd, CHCH ₂), 2.76 (2H, dd CHCH ₂), 1.27 (3H, t, NCH₂ CH ₃); and

ESIMS: M+1: 419.

Example 3 Preparation of Morpholino6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,7-naphthyridine-3-carboxamide(Example 3)

a) 2,5-Dichloropyridine-4-carboxylic acid

At −75° C., 2,5-dichloropyridine (3.7 g) was added to a solution ofbutyl lithium (25 ml, 1M) and N,N,N′,N″,N″-pentamethyldiethylenetriamine(5.3 ml) in THF (50 ml) under a nitrogen atmosphere at −75° C. and thereaction mixture stirred for 2 h, poured onto dry ice, and water (50 ml)added. The aqueous phase was washed with diethyl ether; acidified to pH2 and the white solid filtered off dried to give the product (2.5 g), aknown compound, for the next reaction, without further characterizationother than ascertaining that the compound was one spot by tlc with theexpected molecular weight (M−1) of 190.

b) Ethyl 3-(2,5-dichloropyridin-4-yl)-3-oxopropionoate

A mixture of 2,5-dichloropyridine-4-carboxylic acid (2 g) and SOCl₂ (10ml) and 1 drop of DMF were heated under reflux for 2 h, and all SOCl₂and DMF removed under reduced pressure to give the crude acid chlorideas the remaining residue. Separately, a suspension of potassium ethylmalonate (5 g) in acetonitrile (100 ml) was cooled to 0° C., magnesiumchloride (4 g) and triethylamine (4 ml) were added, the ice bath removedand the reaction stirred at RT for 3 h. A solution of the crude acidchloride in DCM (25 ml) was carefully added to the malonate slurry andthe resulting mixture stirred at RT overnight. Aqueous HCl (100 ml, 1M)was added and stiffing continued for 1 h. This mixture was thenextracted with diethyl ether (200 ml×3), the organic layer washed withsaturated sodium bicarbonate (200 ml×2) and brine (200 ml), dried overanhydrous magnesium sulfate, filtered and concentrated. The titlecompound was obtained as light yellow oil (1.6 g) which was on-reactedwithout further purification and without further characterization otherthan ascertaining that the compound was one spot by tlc with theexpected molecular weight (M−1) of 260.

c) Preparation of3-(2,5-dichloropyridin-4-yl)-2-(2-ethylamino)-ethylene-1-yl)-3-oxopropanoate

A solution of ethyl 3-(2,5-dichloropyridin-4-yl)-3-oxopropanoate (1.6 g)and triethylorthoformate (1.6 mL) in acetic anhydride (6 ml) was heatedat 130° C. for 2 h with stiffing. After cooling to RT, all solvent wasremoved in vacuo, toluene added, removed in vacuo, and this procedurerepeated once more. The remaining crude residue was re-dissolved in THF(50 mL) and the ethyl amine (70% in water, 5 ml) was added dropwise withstiffing at RT and stiffing continued further for 3 h. The reactionmixture was then extracted with DCM (200 ml×3), the organic layer washedwith water, dried over magnesium sulfate, filtered, and then all DCMremoved under reduced pressure to give the crude product. This crudeproduct was triturated with diethyl ether to give the pure (A) (1.5 g).

ESIMS: m/z 317.0 [M+H]⁺.

¹H NMR (300 MHz, CDCl₃): δ 11.05 (bs, 0.8H, NH), 9.75 (bs, 0.2H, NH),8.34 (s, 1H), 8.24 (s, 0.5H), 8.19 (s, 0.5H), 7.15 (s, 1H), 3.9-4.1 (m,2H), 3.5-3.6 (m, 2H), 1.41 (t, 3H), 1.03 (t, 3H).

d) Preparation of Ethyl6-chloro-1-ethyl-1,4-dihydro-4-oxo-1,7-naphthyridine-3-carboxylate

A mixture of3-(2,5-dichloropyridin-4-yl)-2-(2-ethylamino)-ethylene-1-yl)-3-oxopropanoate(1.2 g) and potassium carbonate (1 g) was heated at 100° C. in DMF (30ml) for 12 hours. After a standard ethyl acetate/aqueous work-up, theresidue from the evaporated organic layer gave the product, ethyl6-chloro-1-ethyl-1,4-dihydro-4-oxo-1,7-naphthyridine-3-carboxylate (1g).

ESIMS: m/z 281.0 [M+H]⁺.

¹H NMR (300 MHz, CDCl₃): δ 8.80 (s, 1H), 8.53 (s, 1H), 8.33 (s, 1H),4.43 (q, J=6 Hz, 2H), 4.36 (q, J=7 Hz, 2H), 1.63 (t, J=7 Hz, 3H), 1.43(t, J=6 Hz, 3H).

e) Preparation of Morpholino6-chloro-1-ethyl-1,4-dihydro-4-oxo-1,7-naphthyridine-3-carboxamide

A mixture of trimethylaluminium (4 ml, 2M), morpholine (600 mg) in dryDCM (15 ml) were stirred for 1 h at 35° C. under nitrogen. After 1 h,ethyl 6-chloro-1-ethyl-1,4-dihydro-4-oxo-1,7-naphthyridine-3-carboxylate(900 mg) was added and the reaction mixture stirred o/n at the sametemperature. Next day, 1M HCl (10 ml) was added carefully with stirring.After a standard ethyl acetate/aqueous work-up, the residue from theevaporated organic layer gave the morpholino6-chloro-1-ethyl-1,4-dihydro-4-oxo-1,7-naphthyridine-3-carboxamide (700mg).

ESIMS: m/z 322.0 [M+H]⁺.

¹H NMR (300 MHz, CDCl₃): δ 8.84 (s, 1H), 8.29 (s, 1H), 8.11 (s, 1H),4.34 (q, J=7.3 Hz, 2H), 4.22 (m, 1H), 3.3-3.8 (m, 8H), 1.63 (t, J=7.3Hz, 3H).

f) Preparation of Morpholino6-(2,3-Dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,7-naphthyridine-3-carboxamide(Example 3)

A mixture of6-chloro-1-ethyl-1,4-dihydro-morpholino-4-oxo-1,7-naphthyridine-3-carboxamide(100 mg) and 2-aminoindane (in excess) was heated at 135° C. for 12 h.The reaction mixture was cooled to RT, ethyl acetate (100 ml) and water(20 ml) was added. The organic phase was separated, concentrated underreduced pressure and subjected to chromatography (SiO₂, 80% ethylacetate in hexane) gave the product Example 3 (22% yield).

LC: Rt=1.55 min

MS: m/z 419.0 [M+H]⁺

¹H NMR (300 MHz, CDCl₃): δ 8.62 (s, 1H, ArH), 8.01 (s, 1H, ArH),7.28-7.18 (m, 5H, 5xArH), 5.57 (bs, 1H, NH). 4.61 (m, 1H, NHCH), 4.27(q, 2H, CH2CH3), 3.80 (m, 6H, morpholino), 3.49 (m, 4H,morpholino+CHCH2), 2.98 (dd, 2H, CHCH2), 1.60 (t, 3H, CH3).

Example 4 Preparation of Methylpiperazino6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxamide(Example 4)

Trimethylaluminium (1 ml, 2M in toluene) was injected via syringe into astirred solution of 1-methylpiperazine (100 mg, 1 mmol) in DCM (10 ml).The reaction was stirred at room temperature for 1 h and then treatedwith ethyl6-(2,3-dihydro-1H-inden-2-ylamino)-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxylate(188.5 mg, 0.5 mmol). The resulting mixture was stirred at roomtemperature for 16 h and then poured into 5 ml of 2M HCl aq. The organiccompound was extracted with ethyl acetate (3×10 ml) and the combinedextract was dried over MgSO₄, filtered and concentrated under reducedpressure to afford the crude oil (120 mg crude). Chromatography of asmall quantity of the crude gave the desired product (40 mg).

ESIMS: m/z=432.0 [M+H]⁺.

¹H-NMR (300 MHz, CDCl₃): δ 8.15 (d J=2.2, 1H), 8.09 (s, 1H), 7.80 (d,J=2.2 Hz, 1H), 7.15-7.25 (m, 4H), 4.30-4.50 (m, 4H), 3.78 (s, 2H),3.35-3.50 (m, 4H), 2.86 (dd, 1.1 Hz, 2H), 2.48 (t, J=2 Hz., 4H), 2.30(s, 3H), 1.47 (t, J=2.4 Hz, 3H).

Example 5 Preparation of Cyclopropylamino6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxamide(Example 5)

Trimethylaluminium (1 ml, 2M in toluene) was injected via syringe into astirred solution of cyclopropylamine (57 mg, 1 mmol) in DCM (10 ml). Thereaction was stirred at room temperature for 1 h and then treated withethyl6-(2,3-dihydro-1H-inden-2-ylamino)-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxylate(188.5 mg, 0.5 mmol). The resulting mixture was stirred at roomtemperature for 16 h and then poured into 5 ml of 2M HCl aq. solution.The organic compound was extracted with ethyl acetate (3×10 ml) and thecombined extract was dried over MgSO₄, filtered and concentrated underreduced pressure to afford the crude oil (150 mg crude). Chromatographyof a small quantity of the crude gave the desired product (80 mg).

ESIMS: m/z=389.0 [M+H]⁺.

¹H-NMR (300 MHz, CDCl₃): δ 10.01 (s, 1H), 8.81 (s, 1H), 8.18 (s, 1H),7.80 (s, 1H), 7.15-7.25 (m, 4H), 4.30-4.51 (m, 4H), 3.42 (dd, J=5.0, 5.0Hz, 2H), 2.88-2.97 (m, 3H), 1.45 (t, J=4.2 Hz, 3H); 0.77-0.82 (m, 2H),0.60-0.65 (m, 2H).

Example 6 Preparation of Diethylamino6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxamide(Example 6)

Trimethylaluminium (1 ml, 2M in toluene) was injected via syringe into astirred solution of diethylamine (73 mg, 1 mmol) in DCM (10 ml). Thereaction was stirred at room temperature for 1 h and then treated withethyl6-(2,3-dihydro-1H-inden-2-ylamino)-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxylate(188.5 mg, 0.5 mmol). The resulting mixture was stirred at roomtemperature for 16 h and then poured into 5 ml of 2M HCl aq. solution.The organic compound was extracted with ethyl acetate (3×10 ml) and thecombined extract was dried over MgSO₄, filtered and concentrated underreduced pressure to afford the crude oil (135 mg crude). Chromatographyof the crude gave the desired product (100 mg)

ESIMS: m/z=405.0 [M+H]⁺.

¹H-NMR (300 MHz, CDCl₃): δ 8.15 (d, J=2.2 Hz, 1H), 7.85 (s, 1H), 7.76(d, J=2.2 Hz, 1H), 7.09-7.25 (m, 4H), 4.56 (d, J=5.6 Hz, 1H), 4.28-4.38(m, 3H), 3.4-3.52 (m, 2H), 3.32-3.40 (m, 4H), 2.85 (dd, J=11, 3 Hz, 2H),1.39 (t, J=5.6 Hz, 3H); 1.38 (t, J=5 Hz, 3H), 1.07 (t, J=5 Hz, 3H).

Example 7 Preparation of Ethyl6-(3,4,5-trimethoxybenzoylamide)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate(Example 7)

To the solution of ethyl1-ethyl-1,4-dihydro-6-amino-4-oxo-1,8-naphthalidine-3-carboxylate (261mg, 1 mmol) in dichloromethane (5 ml) was treated with3,4,5-trimethoxybenzoyl chloride (460 mg, 2 mmol) at 5° C. The reactionmixture was then heated to 60° C. for 16 h. The reaction mixture waspoured into ice and the product was extracted with ethyl acetate (3×10ml). The combined extract was dried over MgSO₄ and concentrated underreduced pressure to afford the crude product (220 mg). Chromatography ofa small quantity of the crude using 10% ethyl acetate in hexane affordedthe desired product (30 mg).

ESIMS: m/z=455.9 [M+H]⁺.

¹H-NMR (300 MHz, CDCl₃): δ 9.69 (s, 1H), 9.42 (s, 1H), 8.87 (s, 1H),8.68 (s, 1H), 7.24 (s, 1H), 7.14 (s, 1H), 4.51 (q, J=9, 5 Hz, 2H), 3.88(s, 9H), 3.38-3.47 (m, 2H), 1.48 (t, J=6 Hz, 3H), 1.18 (t, J=6 Hz, 3H).

Example 8 Preparation of 4-fluorophenylamino6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxamide(Example 8)

Trimethylaluminium (1 ml, 2M in toluene) was injected via syringe into astirred solution of 4-fluoroaniline (111 mg, 1 mmol) in DCM (10 ml). Thereaction was stirred at room temperature for 1 h and then treated withethyl6-(2,3-dihydro-1H-inden-2-ylamino)-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxylate(188.5 mg, 0.5 mmol). The resulting mixture was stirred at roomtemperature for 16 h and then poured into 5 ml of 2M HCl aq. Solution.The organic compound was extracted with ethyl acetate (3×10 ml) and thecombined extract was dried over MgSO₄, filtered and concentrated underreduced pressure to afford the crude (160 mg). Chromatography of a smallquantity of the crude gave the desired product (90 mg).

ESIMS: m/z=443.0 [M+H]⁺.

¹H-NMR (300 MHz, CDCl₃): δ 8.86 (s, 1H), 8.20 (d, J=1.8 Hz., 1H), 7.83(d, J=1.8 Hz, 1H), 7.69-7.74 (m, 2H), 7.16-7.24 (m, 4H), 6.98-7.04 (t,J=7 Hz, 2H), 4.50 (q, J=14, 6 Hz, 2H), 4.44 (s broad, 2H), 3.45 (d, J=14Hz, 2H), 2.91 (d, J=14 Hz, 2H), 1.46 (t, J=8 Hz, 3H).

Example 9 Preparation of4-biphenylamino-6-(2,3-dihydro-1H-inden-2-ylamino)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxamide(Example 9)

Trimethylaluminium (1 ml, 2M in toluene) was injected via syringe into astirred solution of 4-aminobiphenyl (169 mg, 1 mmol) in DCM (10 ml). Thereaction was stirred at room temperature for 1 h and then treated withethyl6-(2,3-dihydro-1H-inden-2-ylamino)-1,4-dihydro-4-oxo-1,5-naphthyridine-3-carboxylate(188.5 mg, 0.5 mmol). The resulting mixture was stirred at roomtemperature for 16 h and then poured into 5 ml of 2M HCl aq. solution.The organic compound was extracted with ethyl acetate (3×10 ml) and thecombined extract was dried over MgSO₄, filtered and concentrated underreduced pressure to afford the crude product (140 mg). Chromatography ofa small quantity of the crude gave the desired product (50 mg).

ESIMS: m/z=501.0 [M+H]⁺.

¹H-NMR (300 MHz, CDCl₃): δ 8.90 (s, 1H), 8.21 (d, J=3.5 Hz, 1H),7.84-7.88 (m, 3H), 7.57-7.61 (m, 4H), 7.41 (t, J=6.8 Hz, 3H), 7.16-7.32(m, 5H), 4.52 (q, J=10, 6 Hz, 2H), 4.37-4.44 (m, 2H), 3.46 (dd, J=15, 5Hz, 2H), 2.92 (dd, J=15, 3 Hz, 2H), 1.52 (t, J=6 Hz, 3H).

Example 10 Preparation of Ethyl6-(isobutyrylamide)-1-ethyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate(Example 10)

To the solution of ethyl1-ethyl-1,4-dihydro-6-imino-4-oxo-1,8-naphthalidine-3-carboxylate (261mg, 1 mmol) in dichloromethane (5 ml) was treated with isobutyrylchloride (213 mg, 2 mmol) at 5° C. The reaction mixture was then heatedto 60° C. for 16 h. The reaction mixture was poured into ice and theproduct was extracted with ethyl acetate (3×10 ml). The combined extractwas dried over MgSO₄ and concentrated under reduced pressure to affordthe crude product (220 mg). Chromatography of a small quantity of thecrude using 10% ethyl acetate in hexane afforded the desired product(NMR data indicates that the product was a mixture of cis andtrans-isomers (due to amide linkage).

ESIMS: m/z=332.0 [M+H]⁺.

¹H-NMR (300 MHz, CDCl₃): δ 9.74 (s), 9.54 (d, J=2.5 Hz.), 9.3-9.31 (m),8.85 (s), 8.72 (d, J=2.5 Hz.), 8.66 (s), 8.62 (d, J=2.5 Hz.), 8.59 (s),4.43-4.53 (m, 2H), 4.28-4.35 (m, 2H), 3.41-3.50 (m, 2H), 2.77-2.86 (m,1H), 2.60-2.69 (m, 1H), 1.41-1.50 (m), 1.31-1.36 (t), 1.18-1.25 (m).

Biological Data

Screening of the Anxiolytic Effect

Light Dark Test

The light dark paradigm is based on a conflict between the innateaversion of rodents to brightly illuminated areas and on the spontaneousexploratory behaviour of the mice. If given a choice between a largebrightly compartment versus a small dark compartment they spontaneouslyprefer the dark part. Anxiolytic compounds have been found to increasethe number of entries into the bright compartment and the total timespent there. Anxiogenic compounds were observed to work in the oppositeway.

The apparatus consists of two PVC (polyvinylchloride) boxes (19×19×15cm) covered with Plexiglas. One of these boxes is darkened. The otherbox is illuminated by 100 W desk lamp placed 15 cm above and providingan illumination of about 4400 Lux. An opaque plastic tunnel (5×7×10 cm)separates the dark box from the illuminated one.

Animals were placed individually in the lit box, with head directedtowards the tunnel. The time spent in the lit box and the number oftransitions between the two boxes was recorded over a 5 min period afterthe first entry of the animal in the dark box. The total walked distancein the lit box was also recorded Animals scored without entry into thelit box were excluded from the analysis.

Test Compounds and Treatment The compounds in Table 1 were tested in thelight-dark test (indicated in the LD column).

+=a significant anxiolytic effect in one of the three parametersmeasured in the LD model, ++ represents a significant effect in 2parameters and +++ is significance in all three. The parameters are:time spent in the lit area, number of transitions into the lit area, ortotal walked distance in the lit area. The minimum effective dose inmg/kg is also shown.

The test compound was prepared in 5% PEG400-0.9% NaCl. It wasadministrated orally, 60 minutes before the implementation of the test.

Mean±sem of 10 mice

Elevated Plus Maze

The Elevated Plus Maze (EPM) situation rests on the conflict between theinnate tendencies of rodents to explore novel environments and avoidopen and brightly lit areas. In this task the mouse is placed in thecentre of the maze. From here it can walk down any of four runways. Twoof the arms are well lit and open, and the other two are enclosed anddimly lit. Mice prefer the closed arms but will venture out into theopen arms. The amount of time spent in the open arms and the number oftimes the mice enter the open arms are recorded. The total walkeddistance in the open arms is also recorded. “Anxious” mice will spendlittle time in the open arms and make very few entries into the openarms.

The apparatus is made of polyvinylchloride materials and consists offour equal exploratory arms (45×10 cm) which are all interconnected by asmall platform (10×10 cm). Two arms are open and two others are closedwith walls (30 cm high). The apparatus is placed 66 cm above the floor.A videotracking system is used to record the test (ViewPoint, France).The video camera is placed at 2.50 m above the equipment and connectedto the computer via a video capture card (Pinnacle Systems, France).

A trial consists of placing an animal on the central platform facing aclosed arm. The number of entries and the duration spent in open armsare automatically recorded by a videotrack system during a 5 minutesperiod.

The apparatus is cleaned between each animal using alcohol (70%).

Test Compounds and Treatment

The compounds in Table 1 were tested in the Elevated plus maze(indicated in the EPM column). +=a significant anxiolytic effect in oneof the three parameters measured in the LD model, ++ represents asignificant effect in 2 parameters and +++ is significance in all three.The parameters are: time spent in the open arms, number of transitionsinto the open arms, or total walked distance in the open arms. Theminimum effective dose in mg/kg is also shown.

The test compound was prepared in 5% PEG400-0.9% NaCl.

It was administrated orally, 60 minutes before the implementation of thetest. Mean±sem of 10 rats.

Marble Burying

The Marble Burying test is used as a model for both anxiety andobsessive compulsive disorders. Mice have a natural tendency to burymarbles under the bedding when placed in a cage with rows of evenlyspaced marbles on the floor. Suppression of this spontaneous burying hasbeen used as a measure of anxiolytic drug action. Mice pre-treated withbenzodiazepines and different classes of antidepressants bury lessmarbles when compared to the control mice

The apparatus consists of transparent polycarbonate cages (30 cm×18cm×19 cm) containing a 5 cm layer of fine sawdust bedding and 20 glassmarbles (diameter: 1.5 cm) spaced evenly along the walls of the cage.Each animal is placed individually in the cage where it remains for a 20min test session. On termination of the test session the animals areremoved from the cage and the number of marbles at least two-thirdsburied in the sawdust is recorded.

Test Compounds and Treatment

Example 1 was tested in the Marble Burying model. The minimum effectivedose in mg/kg is indicated in the MB column in Table 1.

The test compound was prepared in 5% PEG400-0.9% NaCl.

It was administrated orally, 60 minutes before the implementation of thetest. Mean±sem of 10 mice.

Screening of the Sedative or Stimulating Effect of Compounds in theModified Open Field

Open Field

The open field (dark) is used to measure the spontaneous motor activityof mice in a quiet, dark environment. This system is useful fordiscriminating the sedating or stimulating properties of test compoundson spontaneous locomotion and can thus provide a preliminary indicationof potentially adverse effects such as sedation.

The apparatus is an open plexiglass cage (52×52 cm) with 40 cm walls.The animal's movements are tracked by a computerised video trackingsystem, consisting of an overhead camera, diode sensors placedunderneath the floor of the cage, computer and video analyser software(ViewPoint, France). The video camera is placed at 2.50 m above the cageand connected to the computer via a video capture card (PinnacleSystems, France). The video tracking system is set in a way that thefloor of the OF is divided into nine equal squares. The total number ofcrossed squares and the total walked distance are recorded.

Each animal is singly placed in a corner of the apparatus and itslocomotor activity is automatically recorded over a period of 20minutes.

The apparatus is cleaned between each animal with alcohol (70%).

Test Compounds and Treatment

The below items were tested in the Open Field as indicated by an entryin the OF column NS=no sedation; S=sedation. The maximum non-sedatingdose in mg/kg is shown.

Test compound was prepared in 5% PEG400-0.9% NaCl. It was administeredorally, 60 minutes before the implementation of the test.

Mean±sem of 10 mice

(*N.B. NT means “Not Tested”)

TABLE 1 Example EPM Number Structure LD OF rat MB 1

 ++0.01 NS 100 +++0.1 +++1 2

+++30  S  5 NT NT 3

++10  NT NT NT  4*

++20  NT NT NT  5*

+20 NT NT NT  6*

++20  NS  20 NT NT  7*

++20  S  20 NT NT  8*

++20  NS  20 NT NT  9*

+++20  NS  20 NT NT 10*

+++20  NS  20 NT NT *20 mg/kg is the only dose tested in the LD box andOF.

The claims defining the invention are as follows:
 1. A method oftreating a central nervous system disorder including the step ofadministering to a patient in need thereof a compound of formula

or a pharmaceutically acceptable salt thereof, wherein the centralnervous system disorder is selected from the group consisting of anxietyand depressive disorders.
 2. A method according to claim 1 wherein thecentral nervous system disorder is an anxiety disorder.
 3. A methodaccording to claim 1 wherein the central nervous system disorder is adepressive disorder.
 4. A method according to claim 1 wherein treatmentincludes combination therapy with at least one of a muscle relaxant,anticonvulant, hypnotic, anaesthetic, analgesic and anxiolytic.
 5. Amethod according to claim 2, wherein the anxiety disorder is selectedfrom the group consisting of panic disorder with or without agoraphobia,agoraphobia without history of panic disorder, animal and other phobias,obsessive-compulsive disorder, stress disorder, and generalized orsubstance induced anxiety disorder.
 6. A method according to claim 5,wherein the other phobias is a social phobia.
 7. A method according toclaim 5, wherein the stress disorder is a post-traumatic or acute stressdisorder.
 8. A method according to claim 3, wherein the depressivedisorder is selected from the group consisting of single-episode orrecurrent major depressive disorder, dysthymic disorder, bipolar I andbipolar II manic disorders, and cyclothymic disorder.